Case Stretching
Bart Bobbitt
sizing die:
: I deliberately set
: the full length sizing die short of the shoulder.
I would bet that when this is done, the resized cases will have headspace
longer than what the chamber has. My reasoning is based on actual case
measurements when a FL die is so set. When the bolt is closed on one of
these cases, the locking lugs bear quite hard on their receiver surfaces.
And any lubricant is often completely displaced. What happens is the lugs
and their mating surfaces in the receiver start to wear; chamber headspace
opens up.
Having seen more than a few rifles that have experienced this problem,
some having headspace open up beyond the `no-go' point and occasionally
past the `field-gage' point, I strongly caution folks not to back their
FL die too much. RCBS' Precision Mic is an excellent tool to adjust FL
dies to size a case about .001-in. less than chamber headspace. Otherwise,
strip the bolt and close it on a resized case very gently; if any resistance
is felt, your case's headspace is too long for the chamber.
When FL dies are backed out too far, the shoulder moves forward. This
happens because the case body is reduced in diameter and the brass has to
go someplace; it lengthens the case body making the shoulder move forward.
I've never seen a rifle shoot as accurate with `extra-long' headspaced
cases as those where the case headspace is about .001 or so shorter than
chamber headspace. Those longer cases preload the bolt, and, if the bolt
face isn't trued up with the chamber axis, the out-of-square case head
will probably not be oriented the same as its previous firing. This causes
the barreled action to whip differently than it did before with the same
case. With a non-trued bolt face but non-square headed cases whose headspace
is a tad shorter than the chamber's, the same thing happens, but to a
lesser degree.
BB
gus Baird
In article <C58zB...@fc.hp.com> ba...@hpfcla.fc.hp.com (Bart Bobbitt) writes:
>gus Baird (g...@prism.gatech.edu) wrote about a .22-250's tapered case:
>
>: >Is this a characteristic of this round? Does the heavy
>: >case taper have anything to do with it?
>
>: Practically everything to do with it. My 22-250 did the same - is partly
>: why I'm practically overboard now for improved cases - nearly no taper.
>
>Can you please explain why a case with more taper would have anything to
>do with the problem of case length variances as opposed to a case with
>virtually no taper?
The case without taper has less tendency to stretch when fired.
If cases don't do that, then they'll tend to stay the same length,
assuming they started off at the same length.
Just after ignition, cases tend to be all the way forward in the
chamber - case shoulder against chamber shoulder. A tapered case
will "wedge" itself back, putting its head hard against the bolt
face, as pressure builds: inclined plane effect. The case shoulder
will then be formed forward to fill the chamber again. Untapered or
slightly tapered cases don't do this. I have had to oil cases being
fired in improved chambers when I *wanted* them to set back so as
to fill the chamber on initial firing. Jokesters have asserted
that radically improved cases don't need a bolt except to hold the
firing pin: the cases grip the chamber walls so tightly that the case
won't back out.
>
>: BTW, you can have that chamber improved. Straightening out those cases
>: will give you nearly infinite case life if you don't load so hot as
>: to have the primers falling out of the pockets. Ballistix of the
>: 22-250Improved are a match for the .220 Swift, but it's a little
>: easier on barrels and a *lot* easier on cases - that case *really*
>: has the taper!
>
>The .22-.250 burns about the same amount of powder as the .220 Swift.
>How can it be easier on barrels? The improved version will certainly
>wear out a barrel faster than the standard version given equal pressures.
>And it certainly would be less accurate with the 50-55 gr. bullets.
I dunno why it should be less accurate: haven't heard any reports to that
effect. As to barrel wear: squared-up cases appear to be a little easier
on barrels when we're getting the same bullet speed. Odd. The explanation
is a little problematical... One hypothesis was that if the line of the
shoulder be extended, you get more erosion if it meets the barrel, less
if it meets the case mouth: sort of a blasting effect. That's an old one.
I think it's rather because we get more speed with less powder if the
case has a sharp shoulder, for extruded powders. The improved cases
I use have the 40-degree "Ackley" shoulder, right square. So I guess
it's less the lack of taper than it is the sharp shoulder. I wonder
whether the 28-degree "RCBS" improved cases show this advantage.
>
>`Nearly infinite life;' is that close to 1,234,567,890 reloads per case?
>Just kidding.............
>
>Some years ago, I had a .22-250 and I never had short case life. I would
>usually get 40 or more loads per case with maximum loads. Case length
>grew about .001-in. every two or three reloads. And I used a full-length
>sizing die. But the interesting part about this was the pressure ring
>and shoulder diameters of my fired cases were reduced only about .002-in.
>by my sizing die and the shoulder was not set back at all.
Did you have to trim those cases? I've never had to trim an improved case,
even after upwards of 20 firings. They get retired when the primer pockets
get too loose.
I think we will get long case life whenever we avoid working cases with
repeated stretching and sizing back down, and even a tapered one will
go a good while if we don't set that shoulder back. .303 Brit experience
with that loooong chamber (for desert sand?) backs this up: putting those
cases back to spec every reloading will use them up pronto.
But despite this, there seems to be a tendency for tapered cases to
stretch more than straight ones even if we resize optimally. I've read
of "flow" of brass down that slope towards the case mouth as one
explanation of the phenomenon. I just don't know, myself.
So: did you have to trim? If we were both getting very long life, you
with tapered cases and me with straight ones, but you had to trim and
I didn't, then maybe there is something to that pretty shaky sounding
notion.
>
>So, I think that if some folks have a short case-life problem and other
>folks don't, even if the same cartridge is used, there must be a difference
>in barrel chambers and tools/processes. Otherwise, everybody who used the
>same cartridge would have the same experiences in reloading. But that
>just isn't the situation.
>
>BB
--
gus Baird, College of Computing
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!gus
ARPA: g...@cc.gatech.edu
K. Karcich
#K. Karcich (kk...@troi.cc.rochester.edu) wrote about setting his
#sizing die:
#: I deliberately set
#: the full length sizing die short of the shoulder.
#I would bet that when this is done, the resized cases will have headspace
#longer than what the chamber has. My reasoning is based on actual case
#measurements when a FL die is so set. When the bolt is closed on one of
#these cases, the locking lugs bear quite hard on their receiver surfaces.
#And any lubricant is often completely displaced. What happens is the lugs
#and their mating surfaces in the receiver start to wear; chamber headspace
#opens up.
Nope. The cases chamber *easily* and the bolt is not forced closed when this is
done correctly. The neck is sized back about half way, the die reduces the
outside diameter of the case, but the sholder stays fireformed.
And if you can cause lug wear this way and cause headspace to
open up, you are either using actions made of silly puddy or you have super
human strength.
#Having seen more than a few rifles that have experienced this problem,
Ok, I have to ask. What rifles and What Actions. I'll be honest Bart, I don't
think you have seen any rifles or actions that increased headspace this way
unless you have been putting lapping compound on your cases.
#some having headspace open up beyond the `no-go' point and occasionally
No Way. If this is true you have another mechanical problem.
#past the `field-gage' point, I strongly caution folks not to back their
#FL die too much. RCBS' Precision Mic is an excellent tool to adjust FL
#dies to size a case about .001-in. less than chamber headspace. Otherwise,
#strip the bolt and close it on a resized case very gently; if any resistance
#is felt, your case's headspace is too long for the chamber.
#When FL dies are backed out too far, the shoulder moves forward. This
#happens because the case body is reduced in diameter and the brass has to
#go someplace; it lengthens the case body making the shoulder move forward.
This is adjusted way out of range. Just don't push the sholder back. I stated
that the resizing gauge has to be adjusted to reflect the specific chamber
that your dealing with.
#I've never seen a rifle shoot as accurate with `extra-long' headspaced
#cases as those where the case headspace is about .001 or so shorter than
#chamber headspace. Those longer cases preload the bolt, and, if the bolt
#face isn't trued up with the chamber axis, the out-of-square case head
#will probably not be oriented the same as its previous firing. This causes
#the barreled action to whip differently than it did before with the same
#case. With a non-trued bolt face but non-square headed cases whose headspace
#is a tad shorter than the chamber's, the same thing happens, but to a
#lesser degree.
None of my rifles are target rifles, but they all shoot very accurately within
the limits of very light weight rifles, and my brass lasts forever even with hot
loads.
regards,
Ken Karcich
#BB
#
Bart Bobbitt
: Nope. The cases chamber *easily* and the bolt is not forced closed when this is
: done correctly. The neck is sized back about half way, the die reduces the
: outside diameter of the case, but the sholder stays fireformed.
: And if you can cause lug wear this way and cause headspace to
: open up, you are either using actions made of silly puddy or you have super
: human strength.
Perhaps your dies and process are different than mine. My cases do get
longer in headspace if only partially sized in a FL die. The shoulder
diameter from fired to sized dimension also gets smaller.
That's silly `putty,' not puddy.
: Ok, I have to ask. What rifles and What Actions. I'll be honest Bart, I don't
: think you have seen any rifles or actions that increased headspace this way
: unless you have been putting lapping compound on your cases.
Those Remington, Winchester, Mauser and Springfield actions may very well
been forged from silly putty; I didn't do any hardness tests on them. But
these are the makes I've seen headspace open up on. In each situation, the
user was backing off his FL die to partial size the cases. And they each
noted that closing the bolt was harder than with new factory ammo. And it's
fine with me if you don't believe me; I'm just telling things like I see 'em.
: #some having headspace open up beyond the `no-go' point and occasionally
: No Way. If this is true you have another mechanical problem.
:
: #past the `field-gage' point, I strongly caution folks not to back their
: #FL die too much. RCBS' Precision Mic is an excellent tool to adjust FL
: #dies to size a case about .001-in. less than chamber headspace. Otherwise,
: #strip the bolt and close it on a resized case very gently; if any resistance
: #is felt, your case's headspace is too long for the chamber.
Well, there's only a few thousandths of an inch between no-go and field
gage dimensions. Depending on where the new chamber started, I may not
have too far to go to get beyond field gage tolerances; less to go past
no-go.
: #When FL dies are backed out too far, the shoulder moves forward. This
: #happens because the case body is reduced in diameter and the brass has to
: #go someplace; it lengthens the case body making the shoulder move forward.
: This is adjusted way out of range. Just don't push the sholder back. I stated
: that the resizing gauge has to be adjusted to reflect the specific chamber
: that your dealing with.
I agree. As long as a resized case has headspace no longer than the chamber,
all is well.
: #I've never seen a rifle shoot as accurate with `extra-long' headspaced
: #cases as those where the case headspace is about .001 or so shorter than
: #chamber headspace. Those longer cases preload the bolt, and, if the bolt
: #face isn't trued up with the chamber axis, the out-of-square case head
: #will probably not be oriented the same as its previous firing. This causes
: #the barreled action to whip differently than it did before with the same
: #case. With a non-trued bolt face but non-square headed cases whose headspace
: #is a tad shorter than the chamber's, the same thing happens, but to a
: #lesser degree.
: None of my rifles are target rifles, but they all shoot very accurately within
: the limits of very light weight rifles, and my brass lasts forever even with hot
: loads.
Brass lasting forever? Well now, it's my turn to be honest with you. Just
how long is forever? And how hot is hot?
You don't need a target rifle to tell the difference. Just a top quality
barrel, a trued up action, properly bedded receiver, decent trigger, and
ammunition that shoots less than .3 MOA at 100 yards.
dxbojan
#
#I started to reload some .22-250 recently and on a whim I checked the
#length of my cases. Some of them had stretched to as much as .010
#
My problem is different. I have measured a bunch of new cases for
.223. I do not know why but the length variation is amazing. The .223
shell has to be 1.760 in length and I get lengths from 1.750 to 1790.
The range of 1.770-1.780 is the most common. That presents a problem
in crimping the FMJ right on the crimp marks. The length differences
are almost exclusively in the neck of the shell. They all load just
fine in my HBAR but the differences bother me.
Now, I reload the .300 Win. Mag. and the case variations there are
much, much less. After 5-6 shots with the same case the case
stretching is still from minimal to non-existant. And my loads are not
mild at all.
Dimitar Bojantchev
dxb...@snrm39.pacbell.com
Bart Bobbitt
: The case without taper has less tendency to stretch when fired.
: If cases don't do that, then they'll tend to stay the same length,
: assuming they started off at the same length.
This differes from what I've seen with cases having different tapers.
They've all got shorter in case length after firing.
: Just after ignition, cases tend to be all the way forward in the
: chamber - case shoulder against chamber shoulder. A tapered case
: will "wedge" itself back, putting its head hard against the bolt
: face, as pressure builds: inclined plane effect. The case shoulder
: will then be formed forward to fill the chamber again. Untapered or
: slightly tapered cases don't do this. I have had to oil cases being
: fired in improved chambers when I *wanted* them to set back so as
: to fill the chamber on initial firing. Jokesters have asserted
: that radically improved cases don't need a bolt except to hold the
: firing pin: the cases grip the chamber walls so tightly that the case
: won't back out.
Same comment as above.
: I dunno why it should be less accurate: haven't heard any reports to that
: effect.
Well, you just heard mine. The reason is that with the same twist and
bullet, but a higher velocity, the bullet will spin faster. A faster
spinning bullet will have more centrifugal force due to its unbalance.
That's why the twist should be slowed down by 10% if the velocity is sped
up by 10%. But if you don't have a one-third MOA rifle in the first place,
noting any accuracy change will be extremely hard to detect.
: As to barrel wear: squared-up cases appear to be a little easier
: on barrels when we're getting the same bullet speed. Odd. The explanation
: is a little problematical... One hypothesis was that if the line of the
: shoulder be extended, you get more erosion if it meets the barrel, less
: if it meets the case mouth: sort of a blasting effect. That's an old one.
How many barrels of the same make and type have you worn out to prove
your theory?
: I think it's rather because we get more speed with less powder if the
: case has a sharp shoulder, for extruded powders. The improved cases
: I use have the 40-degree "Ackley" shoulder, right square. So I guess
: it's less the lack of taper than it is the sharp shoulder. I wonder
: whether the 28-degree "RCBS" improved cases show this advantage.
These sharp-shouldered cartridges have always gotten a lot of interest,
but none have succeded in being successful as a competition cartridge.
I think there is a message somewhere in this observation........
: >Some years ago, I had a .22-250 and I never had short case life. I would
: >usually get 40 or more loads per case with maximum loads. Case length
: >grew about .001-in. every two or three reloads. And I used a full-length
: >sizing die. But the interesting part about this was the pressure ring
: >and shoulder diameters of my fired cases were reduced only about .002-in.
: >by my sizing die and the shoulder was not set back at all.
: Did you have to trim those cases? I've never had to trim an improved case,
: even after upwards of 20 firings. They get retired when the primer pockets
: get too loose.
Yes, I did. The particular combination of FL die and chamber dimensions
had me trimming case length about every 15 loads. But I've had other
cases in different cartridges that didn't need trimming after the initial
trim. They would last over 50 reloads and stopped growing after the 7th
firing.
: But despite this, there seems to be a tendency for tapered cases to
: stretch more than straight ones even if we resize optimally. I've read
: of "flow" of brass down that slope towards the case mouth as one
: explanation of the phenomenon. I just don't know, myself.
Measure your cases in all respects after each resizing and firing. Then
you'll find out where the brass is moving from and to.
BB
Bill Burge
#K. Karcich (kk...@troi.cc.rochester.edu) wrote:
#
#Perhaps your dies and process are different than mine. My cases do get
#longer in headspace if only partially sized in a FL die. The shoulder
#diameter from fired to sized dimension also gets smaller.
I was playing with the RCBS headspace mic and some brass from my .308. I was
working on establishing a baseline and a fired case came in at +.007. I then
went about working the FL sizer down to touch the shoulder. I checked the
mic regularly and some of the case grew to +.014 before the die set the
shoulder back where it came from.
/\_/\ ARF!
(0 0)
+==========================----oOO--(_)--OOo----=============================+
\ Bill Burge bu...@qdeck.com / ^--- "and his dog Spot" /
\ NRA#: BKC2376M (&IVOTE) \ "Combat Tupperware keeps my shooting /
\ USPSA#: A-17395 / skills fresher; longer" - "BURP" /
\ \ /
\ Lefty, Glock-lover, combat / "Sure Hon', put down the Casull /
\ 9 Major shooter, NNITO. \ and we can talk about it..." /
\ / (short discussion with my wife) /
+=================================+==========================================+
James Douglas Del-Vecchio
#The case without taper has less tendency to stretch when fired.
#If cases don't do that, then they'll tend to stay the same length,
#assuming they started off at the same length.
(misc about improved cases deleted).
(This is only slightly related, but I figured more people would
read this thread than if I tried to start a new topic. %^)
Barnes, Cartridges of the World, discusses the .22 K-Hornet or Kilborne
Hornet, and two types of .22 Harvey Kay-chuck, which is just the .22
K-hornet or .22 Hornet cut back a bit (to 1.29"?). The K-hornet is
just a hornet fired in a K-hornet chamber, which results in a sharp
shoulderd case
rather than the slight taper of the .22 Hornet. These rounds are for
rifles and revolvers.
1) Would a sharp sholder make any practical difference for
revolvers? The .22 Hornet case taper is so slight anyway.
2) Has anyone shot or had made a revolver for something like
this? It looks fun.
3) .22 K-hornet would be a perfect Dan Wesson type thing. They
already have lots of weird long-cylindered revolvers, this would
just be another one, and a neat one at that. The good thing
about the K-hornet caliber, is that you could use .22 Hornet
factory ammo in it as well as your handloads with the "improved"
case.
4) BTW, anyone seen photos of the Dan Wesson .30 Herrit revolver?
I have no interest in the caliber, but that is quite a neat looking
gun, imo. I've never shot any of their guns or seen them in stores,
but their stainless large (.44) and the wacky long cylinder
(.455 Supermag, etc) look like wonderful things.
I wonder why nobody seems to own any. If the .45 ACP revolver
of theirs is like their large frames with a short cylinder, it
would also be an attractive toy.
Jim
gus Baird
In article <C5E5t...@fc.hp.com> ba...@hpfcla.fc.hp.com (Bart Bobbitt) writes:
>gus Baird (g...@prism.gatech.edu) wrote:
>
>: The case without taper has less tendency to stretch when fired.
>: If cases don't do that, then they'll tend to stay the same length,
>: assuming they started off at the same length.
>
>This differes from what I've seen with cases having different tapers.
>They've all got shorter in case length after firing.
Hey, you're right. On the first firing, anyway. In the longer run
they start to get longer if they're tapered - don't some folks have
to trim cases every few reloadings, eh?
>: I dunno why it should be less accurate: haven't heard any reports to that
>: effect.
>
>Well, you just heard mine. The reason is that with the same twist and
>bullet, but a higher velocity, the bullet will spin faster. A faster
>spinning bullet will have more centrifugal force due to its unbalance.
>That's why the twist should be slowed down by 10% if the velocity is sped
>up by 10%. But if you don't have a one-third MOA rifle in the first place,
>noting any accuracy change will be extremely hard to detect.
I have a hard time believing that our twists, generally rounded off
to the nearest inch of about ten inches, are so nearly dead-on that
a 10% change will uniformly make for *worse* accuracy. Should make
it better about as often. But again, maybe the .3MOA guys *do* have
twists like 9.35 inches - not my area of expertise.
Are you talking observations, or predictions from your model? If the
latter please notice we can get at cross-purposes.
>: As to barrel wear: squared-up cases appear to be a little easier
>: on barrels when we're getting the same bullet speed. Odd. The explanation
>: is a little problematical... One hypothesis was that if the line of the
>: shoulder be extended, you get more erosion if it meets the barrel, less
>: if it meets the case mouth: sort of a blasting effect. That's an old one.
>
>How many barrels of the same make and type have you worn out to prove
>your theory?
You've got it backwards. The "theory" (hypothesis) was cooked up to try
to explain observations, not the other way around. Old-timers noticed
that guys like the 30Holland got shorter barrel life than cases doing
the same job, but which had a sharper shoulder. On observing that the
Holland shoulder was so gentle that it appears to direct flame to
the leade rather than to the inside of the case neck they cooked up
this idea. Certainly not *my* theory - been around longer than I have.
And I imagine they looked at lots of barrels before cooking up this one.
>: I think it's rather because we get more speed with less powder if the
>: case has a sharp shoulder, for extruded powders. The improved cases
>: I use have the 40-degree "Ackley" shoulder, right square. So I guess
>: it's less the lack of taper than it is the sharp shoulder. I wonder
>: whether the 28-degree "RCBS" improved cases show this advantage.
>
>These sharp-shouldered cartridges have always gotten a lot of interest,
>but none have succeded in being successful as a competition cartridge.
>I think there is a message somewhere in this observation........
Something maybe related... The 40-degree case is damned near impossible
to significantly resize (WRT headspace). You may collapse the case
before you move that shoulder back very much. In some circumstances
this may be a disadvantage. It serves as an ultimate check for me,
though: makes it real hard to make a big mistake. The Improved case
does have other disadvantages, too: can be harder to extract, and is
very intolerant of dirty chambers, &c. Not something to get into if
you aren't enamored of it like I am. I don't mind fiddling with them
and don't do rapid-fire competition. It's like keeping an English
sports car - questionable for service but lots of fun.
>: Did you have to trim those cases? I've never had to trim an improved case,
>: even after upwards of 20 firings. They get retired when the primer pockets
>: get too loose.
>
>Yes, I did. The particular combination of FL die and chamber dimensions
>had me trimming case length about every 15 loads. But I've had other
>cases in different cartridges that didn't need trimming after the initial
>trim. They would last over 50 reloads and stopped growing after the 7th
>firing.
>
>: But despite this, there seems to be a tendency for tapered cases to
>: stretch more than straight ones even if we resize optimally. I've read
>: of "flow" of brass down that slope towards the case mouth as one
>: explanation of the phenomenon. I just don't know, myself.
>
>Measure your cases in all respects after each resizing and firing. Then
>you'll find out where the brass is moving from and to.
Don't tease. Have you *seen* what I've heard of: that after lots of
this resizing and trimming you'll find that the necks need reaming?
If that is truly the case(oops!) then that "flow" business is for real.
gus Baird
In article <1993Apr13.0...@henson.cc.wwu.edu> n902...@henson.cc.wwu.edu (James Douglas Del-Vecchio) writes:
>g...@prism.gatech.edu (gus Baird) writes:
>
>#The case without taper has less tendency to stretch when fired.
>#If cases don't do that, then they'll tend to stay the same length,
>#assuming they started off at the same length.
>
>(misc about improved cases deleted).
>
>(This is only slightly related, but I figured more people would
>read this thread than if I tried to start a new topic. %^)
>
>Barnes, Cartridges of the World, discusses the .22 K-Hornet or Kilborne
>Hornet, and two types of .22 Harvey Kay-chuck, which is just the .22
>K-hornet or .22 Hornet cut back a bit (to 1.29"?). The K-hornet is
>just a hornet fired in a K-hornet chamber, which results in a sharp
>shoulderd case
>rather than the slight taper of the .22 Hornet. These rounds are for
>rifles and revolvers.
Hold it! Don't confuse: you can have a tapered case with a sharp
shoulder; you can have straight cases with gentle shoulder slope.
>
>1) Would a sharp sholder make any practical difference for
> revolvers? The .22 Hornet case taper is so slight anyway.
What makes a *big* difference is taper, not shoulder. The .22 Jet
suffered greatly because its taper (lots of) made the cases back
out so hard that stout (not over) loads would lock up the revolver
that was supposed to handle it.
K. Karcich
#K. Karcich (kk...@troi.cc.rochester.edu) wrote:
#: Nope. The cases chamber *easily* and the bolt is not forced closed when this is
#: done correctly. The neck is sized back about half way, the die reduces the
#: outside diameter of the case, but the sholder stays fireformed.
#: And if you can cause lug wear this way and cause headspace to
#: open up, you are either using actions made of silly puddy or you have super
#: human strength.
#Perhaps your dies and process are different than mine. My cases do get
#longer in headspace if only partially sized in a FL die. The shoulder
#diameter from fired to sized dimension also gets smaller.
I think this is true. I have never noted increased headspace.
#That's silly `putty,' not puddy.
Thanks for the SP correction. We should always remain technically correct.
#: Ok, I have to ask. What rifles and What Actions. I'll be honest Bart, I don't
#: think you have seen any rifles or actions that increased headspace this way
#: unless you have been putting lapping compound on your cases.
#Those Remington, Winchester, Mauser and Springfield actions may very well
#been forged from silly putty; I didn't do any hardness tests on them. But
#these are the makes I've seen headspace open up on. In each situation, the
#user was backing off his FL die to partial size the cases. And they each
#noted that closing the bolt was harder than with new factory ammo. And it's
#fine with me if you don't believe me; I'm just telling things like I see 'em.
What I'm saying is that I don't believe that you could increase the headspace
on any of the above actions solely by brass resizing. I think there are other
factors if this is happening to you because I sure havent observed it and I
have not ever heard of this from anyone else.
If brass resizing is so hard on steel, why don't standard loading dies wear out
faster. They do wear, but not very fast. Anyone who has done much reloading
knows that the one thing the gets them is grit on the cases. Do you do your
shooting in a gritty sandy climate Bart? If you have sand in your action, then
I will believe that you are lapping your lugs back. In upstate NY, we don't
have much sand, and we don't have this problem.
Military rifles are designed to last a long time under adverse conditions. If
the above were true, the American Rifleman would not have published a article
about Chinese mausers being used in combat conditions for 50 or so years and
still being functional. And about the only thing that happened to these guns
is that sand and grit wear back the lugs. ( I don't have the citation for the
above but I have it at home and will produce it upon request. )
#: #some having headspace open up beyond the `no-go' point and occasionally
#: No Way. If this is true you have another mechanical problem.
#:
#: #past the `field-gage' point, I strongly caution folks not to back their
#: #FL die too much. RCBS' Precision Mic is an excellent tool to adjust FL
#: #dies to size a case about .001-in. less than chamber headspace. Otherwise,
#: #strip the bolt and close it on a resized case very gently; if any resistance
#: #is felt, your case's headspace is too long for the chamber.
#Well, there's only a few thousandths of an inch between no-go and field
#gage dimensions. Depending on where the new chamber started, I may not
#have too far to go to get beyond field gage tolerances; less to go past
#no-go.
#: #When FL dies are backed out too far, the shoulder moves forward. This
#: #happens because the case body is reduced in diameter and the brass has to
#: #go someplace; it lengthens the case body making the shoulder move forward.
#: This is adjusted way out of range. Just don't push the sholder back. I stated
#: that the resizing gauge has to be adjusted to reflect the specific chamber
#: that your dealing with.
#I agree. As long as a resized case has headspace no longer than the chamber,
#all is well.
Good. We agree on something. Allow me to graciously point out that I never
said that the headspace increased as a result of the proceedure I described.
You jumped to that conclusion.
#: #I've never seen a rifle shoot as accurate with `extra-long' headspaced
#: #cases as those where the case headspace is about .001 or so shorter than
#: #chamber headspace. Those longer cases preload the bolt, and, if the bolt
#: #face isn't trued up with the chamber axis, the out-of-square case head
#: #will probably not be oriented the same as its previous firing. This causes
#: #the barreled action to whip differently than it did before with the same
#: #case. With a non-trued bolt face but non-square headed cases whose headspace
#: #is a tad shorter than the chamber's, the same thing happens, but to a
#: #lesser degree.
#: None of my rifles are target rifles, but they all shoot very accurately within
#: the limits of very light weight rifles, and my brass lasts forever even with hot
#: loads.
All of my rifles have lapped lugs and the face of the action is trued up. I do
not true up the chamber axis since I chamber the gun thru the reciever using
a bushing to line up the reamer extension and a floating coupling in my lathe.
Not quite as good but much better than what the factory does. These guns are
bedded in glass stocks with floated barrel and will shoot under 1 moa with
selected loads. NOTE that these are very light barreled rifles.
#Brass lasting forever? Well now, it's my turn to be honest with you. Just
#how long is forever? And how hot is hot?
20 to 50 reloads, usually when the primer starts falling out. 'Hot' is max
reloading manual + whatever I think appropriate based on case head expansion
measurements.
#You don't need a target rifle to tell the difference. Just a top quality
#barrel, a trued up action, properly bedded receiver, decent trigger, and
#ammunition that shoots less than .3 MOA at 100 yards.
regards, Ken Karcich
Toby Bradshaw
#
#In article <C5E5t...@fc.hp.com> ba...@hpfcla.fc.hp.com (Bart Bobbitt) writes:
# >gus Baird (g...@prism.gatech.edu) wrote:
# >
# >: The case without taper has less tendency to stretch when fired.
# >: If cases don't do that, then they'll tend to stay the same length,
# >: assuming they started off at the same length.
# >
# >This differes from what I've seen with cases having different tapers.
# >They've all got shorter in case length after firing.
#
#Hey, you're right. On the first firing, anyway. In the longer run
#they start to get longer if they're tapered - don't some folks have
#to trim cases every few reloadings, eh?
Trimming has as much to do with excessive neck sizing and rough
expander balls as it does with pressures and shoulder angles. I
shoot competitive benchrest, where pressures are high, and necks
don't stretch enough to warrant trimming (0.005") in 15 or 20
loadings. Using Wilson dies and a minimum or no button (no expander
ball -- bad for accuracy) will solve the problem in a properly
built rifle. Now, necks will get _thicker_ from brass flow due
to pressure, and a "doughnut" will build up at the neck/shoulder
junction. Since I don't seat bullets below the neck, it's a
non-problem for me. The doughnut can't be removed by outside
neck turning, because the brass springs back after the turning
mandrel is withdrawn. Neck reaming can fix the doughnut, but
better to have the chambering reamer made to avoid this problem
by having the bullet base about halfway down the neck. In a
tight-neck BR rifle, there's only 0.0002-0.0005 diameter clearance
for the loaded round, so any discrepancies in neck thickness become
instantly apparent.
# >: I dunno why it should be less accurate: haven't heard any reports to that
# >: effect.
# >
# >Well, you just heard mine. The reason is that with the same twist and
# >bullet, but a higher velocity, the bullet will spin faster. A faster
# >spinning bullet will have more centrifugal force due to its unbalance.
# >That's why the twist should be slowed down by 10% if the velocity is sped
# >up by 10%. But if you don't have a one-third MOA rifle in the first place,
# >noting any accuracy change will be extremely hard to detect.
#
#I have a hard time believing that our twists, generally rounded off
#to the nearest inch of about ten inches, are so nearly dead-on that
#a 10% change will uniformly make for *worse* accuracy. Should make
#it better about as often. But again, maybe the .3MOA guys *do* have
#twists like 9.35 inches - not my area of expertise.
In BR, velocity is usually adjusted to make the twist work, although
it has to be very close in the first place. In cool weather, many
6PPC shooters will switch to a 1-13 twist for the standard 68gr
bullets because the maximum velocity attainable cannot stabilize
the bullet in a 1-14 barrel. In warm weather, everybody shoots a
1-14 in the 6PPC. Velocity is very close to 3250fps for almost
everybody shooting well enough to win. If you don't believe that
1" of twist is important, you haven't shot in competitive rifle
sports.
Toby Bradshaw
Department of Biochemistry and College of Forest Resources
University of Washington, Seattle
to...@u.washington.edu
"A well-educated electorate being necessary to the prosperity of
a free state, the right of the people to keep and read books, shall
not be infringed." Do you believe that restricting people to one book
purchase per month would prevent libel and slander?
Bart Bobbitt
: #Perhaps your dies and process are different than mine. My cases do get
: #longer in headspace if only partially sized in a FL die. The shoulder
: #diameter from fired to sized dimension also gets smaller.
: I think this is true. I have never noted increased headspace.
It is true; use a good micrometer on the cases, and a gage to measure
body wall thickness, too.
: What I'm saying is that I don't believe that you could increase the headspace
: on any of the above actions solely by brass resizing. I think there are other
: factors if this is happening to you because I sure havent observed it and I
: have not ever heard of this from anyone else.
: If brass resizing is so hard on steel, why don't standard loading dies wear out
: faster. They do wear, but not very fast. Anyone who has done much reloading
: knows that the one thing the gets them is grit on the cases. Do you do your
: shooting in a gritty sandy climate Bart? If you have sand in your action, then
: I will believe that you are lapping your lugs back. In upstate NY, we don't
: have much sand, and we don't have this problem.
I think cartridge brass is softer than steel. But when steel bears hard
against steel and there's no lubricant between them, they will wear.
I shoot in all kinds of climates and conditions. But I've never had a
rifle open up in headspace for the life of its barrel. I never said I did
have increasing headspace problems. I did mention I have seen headspace
problems in other folks rifles caused by using cases with longer than
chamber headspace.
: #As long as a resized case has headspace no longer than the chamber,
: #all is well.
: Good. We agree on something. Allow me to graciously point out that I never
: said that the headspace increased as a result of the proceedure I described.
: You jumped to that conclusion.
I said that headspace can increase. If that's jumping, fine. So are
correct conclusions, although you may not have experienced increased
headspace, that doesn't mean it can't happen.
BB
Bart Bobbitt
: Hey, you're right. On the first firing, anyway. In the longer run
: they start to get longer if they're tapered - don't some folks have
: to trim cases every few reloadings, eh?
In the measurements I've made, the case gets a few thousandths shorter
after it's been fired; lengthens about the same when neck sized or a tad
more if FL sized. After several firings and using neck only dies, the
case will stay about the same length after each firing and resizing.
: I have a hard time believing that our twists, generally rounded off
: to the nearest inch of about ten inches, are so nearly dead-on that
: a 10% change will uniformly make for *worse* accuracy. Should make
: it better about as often. But again, maybe the .3MOA guys *do* have
: twists like 9.35 inches - not my area of expertise.
A 1-inch difference in twist for the same velocity can and does make
a difference. For example, benchresters will shoot a 1:14 twist with
a 6PPC in warm weather. In colder weather, they'll switch to a 1:13
twist to speed up the bullet's spin rate to make it stable. They use
the same load and velocity stays the same within a few fps. A few
custom barrel makers are trying different twists to see what shoots
Sierra's .308 155-gr. Palma bullet the best. They are trying one in
13, 13.2, 13.5 13.7 and 14 and the muzzle velocity is pretty close to
2950 fps.
: You've got it backwards. The "theory" (hypothesis) was cooked up to try
: to explain observations, not the other way around. Old-timers noticed
: that guys like the 30Holland got shorter barrel life than cases doing
: the same job, but which had a sharper shoulder. On observing that the
: Holland shoulder was so gentle that it appears to direct flame to
: the leade rather than to the inside of the case neck they cooked up
: this idea. Certainly not *my* theory - been around longer than I have.
: And I imagine they looked at lots of barrels before cooking up this one.
When the .30 Holland (.300 H&H Mag.) was used as a long-range target
cartridge, barrel life before accuracy dropped off was about 1100 or so
rounds. That's the same as the .30-.338 Mag and .300 Win. Mag. There's
quite a difference between these cases. But they used the same powder to
get these barrel life numbers. And there is quite a difference between
shoulder angles and neck length.
I've heard about the .30 Holland having shorter barrel life than similar
cartridges with the same case capacity but with larger and sharper shoulders.
I wouldn't be surprised if the real difference was due to the H&H factory
cartridges using cordite (very erosive, short barrel life) and other
cartridges using standard smokeless rifle powder (not erosive, long barrel
life).
: >: I think it's rather because we get more speed with less powder if the
: >: case has a sharp shoulder, for extruded powders. The improved cases
: >: I use have the 40-degree "Ackley" shoulder, right square. So I guess
: >: it's less the lack of taper than it is the sharp shoulder. I wonder
: >: whether the 28-degree "RCBS" improved cases show this advantage.
: >
: >These sharp-shouldered cartridges have always gotten a lot of interest,
: >but none have succeded in being successful as a competition cartridge.
: >I think there is a message somewhere in this observation........
: Something maybe related... The 40-degree case is damned near impossible
: to significantly resize (WRT headspace). You may collapse the case
: before you move that shoulder back very much. In some circumstances
: this may be a disadvantage. It serves as an ultimate check for me,
: though: makes it real hard to make a big mistake. The Improved case
: does have other disadvantages, too: can be harder to extract, and is
: very intolerant of dirty chambers, &c. Not something to get into if
: you aren't enamored of it like I am. I don't mind fiddling with them
: and don't do rapid-fire competition. It's like keeping an English
: sports car - questionable for service but lots of fun.
I've heard these same comments from the `improved lot' of folks using
these `wonder rounds.'
: >: Did you have to trim those cases? I've never had to trim an improved case,
: >: even after upwards of 20 firings. They get retired when the primer pockets
: >: get too loose.
: >
: >Yes, I did. The particular combination of FL die and chamber dimensions
: >had me trimming case length about every 15 loads. But I've had other
: >cases in different cartridges that didn't need trimming after the initial
: >trim. They would last over 50 reloads and stopped growing after the 7th
: >firing.
: >
: >: But despite this, there seems to be a tendency for tapered cases to
: >: stretch more than straight ones even if we resize optimally. I've read
: >: of "flow" of brass down that slope towards the case mouth as one
: >: explanation of the phenomenon. I just don't know, myself.
: >
: >Measure your cases in all respects after each resizing and firing. Then
: >you'll find out where the brass is moving from and to.
: Don't tease. Have you *seen* what I've heard of: that after lots of
: this resizing and trimming you'll find that the necks need reaming?
: If that is truly the case(oops!) then that "flow" business is for real.
Only when the chamber neck clears the loaded round neck by less than
a thousandth of an inch, like in benchrest rifles. I've taken the same
case and at one setting, fired and reloaded it over 50 times; taking
measurements on case dimensions and chronographing each shot. But this
is in a chamber whose neck is larger than the loaded round neck by about
007-in. Benchresters have more of a problem than the highpower folks do
in this regard.
BB
K. Karcich
#K. Karcich (kk...@troi.cc.rochester.edu) wrote:
#: #Perhaps your dies and process are different than mine. My cases do get
#: #longer in headspace if only partially sized in a FL die. The shoulder
#: #diameter from fired to sized dimension also gets smaller.
#: I think this is true. I have never noted increased headspace.
#It is true; use a good micrometer on the cases, and a gage to measure
#body wall thickness, too.
What is clearly true is that my cases chamber easily, the sholder is not pushed
back, my actions don't wear out and my cases last a long time.
#: What I'm saying is that I don't believe that you could increase the headspace
#: on any of the above actions solely by brass resizing. I think there are other
#: factors if this is happening to you because I sure havent observed it and I
#: have not ever heard of this from anyone else.
#: If brass resizing is so hard on steel, why don't standard loading dies wear out
#: faster. They do wear, but not very fast. Anyone who has done much reloading
#: knows that the one thing the gets them is grit on the cases. Do you do your
#: shooting in a gritty sandy climate Bart? If you have sand in your action, then
#: I will believe that you are lapping your lugs back. In upstate NY, we don't
#: have much sand, and we don't have this problem.
#I think cartridge brass is softer than steel. But when steel bears hard
#against steel and there's no lubricant between them, they will wear.
#I shoot in all kinds of climates and conditions. But I've never had a
#rifle open up in headspace for the life of its barrel. I never said I did
#have increasing headspace problems. I did mention I have seen headspace
#problems in other folks rifles caused by using cases with longer than
#chamber headspace.
Ah! So these were not YOUR rifles. That means that YOU did not see everything
that was done to that rifle. YOU did not see the owner clean the grit out of
the lug recess. YOU are assuming that these rifles failed solely for a single
factor that you know about but you are ignoring everything else that may have
happened. Your chain of evidence linking long cases to these headspace increasesis WEAK. YOUR rifle never demonstrated the above problem , but that did not
stop you from jumping to conclusions and telling the net that this proceedure
was BAD even thou I could have told you that these cases can be chambered with
your fingers. Before you get your mikes out, please put your mind in gear.
#: #As long as a resized case has headspace no longer than the chamber,
#: #all is well.
#: Good. We agree on something. Allow me to graciously point out that I never
#: said that the headspace increased as a result of the proceedure I described.
#: You jumped to that conclusion.
#I said that headspace can increase. If that's jumping, fine. So are
#correct conclusions, although you may not have experienced increased
#headspace, that doesn't mean it can't happen.
You stated that the proceedure that I recommended would increase the case length
possiably leading to failure of the action due to steel on steel wear caused
by the camming action when closing the bolt. You never attempted to get clarification from me on whether or not the cases were hard to chamber.
In any case, I say that the headspace will not increase, in your lifetime, with
even more than normal shooting if you sized your cases with slightly increased
base to shoulder length with a properly fitted rifle, which is cleaned and
properly taken care of, due solely to brass resizing when you chamber the
cartridge. For this to happen would require that something else is wrong like
a soft action or sand or grit in the lug recess which when mixed with oil or
grease makes a lovely agressive lapping compound.
The only commercial rifle that I have ever heard of that had lug galling
problems due to soft bolt lugs are Remington 721's and even then only a few
of these rifles ever demonstrated this problem. I have never seen a Winchester
Mod 70 with this problem or even a Springfield or even a Mauser as these rifles
normally have quite hard bolts. Remember that lug galling or wear and set back
are two different things, with galling being caused by a soft bolt and setback
being caused by a soft reciever. Generally, with setback the bolt gets very
hard to open after firing the gun because the lugs have to be cammed out of
a depression in the lug recess against the lengthened case.
If anyone out there in net land beside BART has ever seen a rifle that increasedits headspace due to brass resizing, I would appreciate E-mail. I will post a
summary.
regards,
Ken Karcich
#BB
Bob DeBula
#Barnes, Cartridges of the World, discusses the .22 K-Hornet or Kilborne
#Hornet, and two types of .22 Harvey Kay-chuck, which is just the .22
#K-hornet or .22 Hornet cut back a bit (to 1.29"?). The K-hornet is
#just a hornet fired in a K-hornet chamber, which results in a sharp
#shoulderd case
#rather than the slight taper of the .22 Hornet. These rounds are for
#rifles and revolvers.
#
#1) Would a sharp sholder make any practical difference for
# revolvers? The .22 Hornet case taper is so slight anyway.
A tapered case in a high pressure .22 cartridge for use in a revolver
is generally a bad idea. The taper allows the case to back out of the chamber
rather easily and this can lead to cylinder binding. The S&W
Model 53 Jet is the classic example of a bad cartridge/revolver
combination, IMHO. I owned a 6" Model 53 and experienced the
joys of cylinder binding (no matter *how* clean and free of
lubricant the chambers were -- despite what S&W will tell you).
That revolver was obnoxious for other reasons as well
(muzzle blast and the truly excruciating sound, as well
as muzzle and cylinder gap flash).
#
#2) Has anyone shot or had made a revolver for something like
# this? It looks fun.
#
I owned an S&W model 17 which a local smith had rechambered for
the .22 K-chuck (I'm not necessarily advocating doing this).
I never experienced any of the problems I had with the S&W Model
53. I sold the revolver years ago (still got some of the brass).
The only problem I recall with that revolver involved bad timing.
The .256 Winchester case looks like the more proper way (again
IMHO) to design a cartridge based on the .357 Magnum case.
#3) .22 K-hornet would be a perfect Dan Wesson type thing. They
# already have lots of weird long-cylindered revolvers, this would
# just be another one, and a neat one at that. The good thing
# about the K-hornet caliber, is that you could use .22 Hornet
# factory ammo in it as well as your handloads with the "improved"
# case.
#
Hmmm, I never used Hornet factory ammo for case forming, I always
used a very mild hornet load.
Of course, these are my opinions and experiences and should by no
means be taken as authoritative on the subject (disclaimer fodder
alert :-).
--
==========================================================================
Disclaimer: These are my views, not the U's
"If it's in the paper it must be true!" --- D. Doright