Greater precision in bullet seating
Bob Bethune
bullet seating die I'm using will turn out several good ones in a row,
and then suddenly push one 0.005 or more too deep, erratically and
unpredictably.
This is a Lee bullet seating die in a Lee Classic rotary press. There
is play in the press. I suspect there is also play in the internals of
the die.
Would the assembled minds recommend a different die? If so, which? Or
are there things I should investigate first?
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Larry The Snake Guy
a set of calipers, keep in mind that the tips of even the best bullets
vary slightly. I don't think it's reasonable to expect the overall
length of your loaded rounds to ever be within .001, nor is it
necessary. I've never used one, but you can get a bullet seating gage
that measures on the ogive of the bullet (where the seating die
presses down) and gives a better measure of practical uniformity.
Others will, no doubt, be able to give you much more info.
Bill Smith
<poi...@comcast.net> wrote:
#I'm trying to keep my bullet seating to .001 of nominal. However
#bullet seating die I'm using will turn out several good ones in a row,
#and then suddenly push one 0.005 or more too deep, erratically and
#unpredictably.
#This is a Lee bullet seating die in a Lee Classic rotary press. There
#is play in the press. I suspect there is also play in the internals of
#the die.
#
#Would the assembled minds recommend a different die? If so, which? Or
#are there things I should investigate first?
Are you measuring from the ogive to base of the case or overall length
of your assembled rounds? The former is a better indication of the
consistency of your bullet seater. The latter can be all over the
place on rounds that are fine. Points on even very well made bullets
can vary a lot, but the ogive to base measurement won't (if they are
flat base bullets, boat tails are a little trickier to measure. Make
sure you seater stem matches the bullets you are using.
It's possible that the rotary press just isn't capable of giving you
the precision you want. A Wilson chamber type bullet seater is what I
use for benchrest ammo;
http://www.lewilson.com/chambertypebulletseater.html
Bill Smith
Tom S.
"Bob Bethune" <poi...@comcast.net> wrote in message
news:gun8oq$811$1...@news.albasani.net...
# I'm trying to keep my bullet seating to .001 of nominal. However
# bullet seating die I'm using will turn out several good ones in a row,
# and then suddenly push one 0.005 or more too deep, erratically and
# unpredictably.
#
# This is a Lee bullet seating die in a Lee Classic rotary press. There
# is play in the press. I suspect there is also play in the internals of
# the die.
#
# Would the assembled minds recommend a different die? If so, which? Or
# are there things I should investigate first?
If there is play in the press, no die is going to compensate for it.
Long ago, I went with a Forster Co-Ax and their micrometer seating dies.
End result: perfection
Blueh...@aol.com
could see the concern but not under.
There could be several factors at play as was suggested...bullet
points aren't perfect. Are all the caseings from the same
manufacturer? Rim thicknesses from different makers can vary and a
thinner rim would give a shorter caseing and vice versa. (So are all
the caseings trimmed to exactly the same length?)
If you suspect the die why not take it apart...clean and inspect it?
Personally I doub't it would be the die itself as it's just a bullet
seater...it's just a stem that you screw down til you get the right
height (unless you are seating and crimping at the same time...which I
never do.)
What type of play in the press are you referring to?
What are you useing to measure your overall cartridge lengths...and is
that tool properly calibrated?
Bob Holtzman
# On Sat, 16 May 2009 20:47:22 +0000 (UTC), Bob Bethune
#<poi...@comcast.net> wrote:
#
# #I'm trying to keep my bullet seating to .001 of nominal. However
# #bullet seating die I'm using will turn out several good ones in a row,
# #and then suddenly push one 0.005 or more too deep, erratically and
# #unpredictably.
...........snip...........
# Are you measuring from the ogive to base of the case or overall length
# of your assembled rounds? The former is a better indication of the
# consistency of your bullet seater. The latter can be all over the
# place on rounds that are fine. Points on even very well made bullets
# can vary a lot, but the ogive to base measurement won't (if they are
# flat base bullets, boat tails are a little trickier to measure. Make
# sure you seater stem matches the bullets you are using.
I'm a little dense today (today?) but what the OP is probably measuring is
from a datum line on the bullet ogive to the base of the case. If so,
what does the bullet base have to do with it?
--
Bob Holtzman
AF9D 8760 0CFA F95A 6C77 E125 BF90 580F 8D54 9279
"If you think you're getting free lunch,
check the price of the beer"
sta...@prolynx.com
turns those out on demand. Other makers are using the sliding sleeve
seater concept now, I still think Bonanza(Forster) has the best
tolerances for production die sets. You CAN get just the seater, see
Midway or the like. To get the best results, it needs to be paired
with the Bonanza Coax press. Lee just has too much tolerance for real
precision work in their presses. You do pay for what you get!
Length is only one item, you need to check bullet runout as well. You
can seat them all to the last decimal, but if they're not square with
the world, they won't shoot as well as they should. The sliding
sleeve helps with that, too.
Stan
wmar...@gmail.com
> ...
A single-stage press (assumption - rifle ammunition?) will have far
less play than most multi-stage presses. I usually use wilson hand-
dies for setting seating depth, but you can a)measure to the ogive
rather than the bullet tip, and b) use just about any die, but in an
"O" or "D" shaped press - far less flexibility/motion, more likely to
have precision loading.
W
Bill Smith
#from a datum line on the bullet ogive to the base of the case. If so,
#what does the bullet base have to do with it?
As far as seating depth goes, nothing. I went off on a tangent
thinking about checking bullet consistency.
He didn't say how he was measuring his loaded rounds.
Bill Smith
Bob Holtzman
# The first question is...why be concerned about under .005 ?? Over I
# could see the concern but not under.
Depends on what level of accuracy the OP is looking for.
# Are all the caseings from the same
# manufacturer? Rim thicknesses from different makers can vary and a
# thinner rim would give a shorter caseing and vice versa. (So are all
# the caseings trimmed to exactly the same length?)
Assuming a rimless rifle cartridge, (can't remember if the OP specified)
none of the above has anything to do with seating depth.
--
Bob Holtzman
AF9D 8760 0CFA F95A 6C77 E125 BF90 580F 8D54 9279
"If you think you're getting free lunch,
check the price of the beer"
Bob Bethune
I'm aiming for a high level of accuracy, the level associated with F-
class or suchlike. Not necessarily benchrest, thought I keep finding a
lot of inspiration in what benchrest shooters do. I want to shoot sub-
MOA very consistently at ranges from 350 to 700 yards, but I don't
need to be in the same hole.
I'm measuring overall length, bullet tip to base of cartridge. I'm
only concerned about catridges that are under length as well as over
length because I want the distance from the bullet to the lands to be
as consistent as possible. Not too long, not too short, but just
right.
I'm loading .308 Winchester; that should answer the rimmed-rimless
question and so forth. I'm loading Sierra Matchking 168 grain boat-
tail hollow-point bullets into Federal cases.
I'm able to get my overall cartridge length, measured base of
cartridge to tip of bullet, on land on 2.800 +/- 0.0005 with the Lee
die, but it takes an unreasonably long time because I have to fiddle
and fiddle and fiddle with each cartridge. I plan to take a look at
some of the equipment mentioned to date, particularly the Foster
micrometer dies.
I'm taking my measurments with a Mitutoyo caliper.
I've never done stats on the uniformity of the overall length of the
Sierra bullets. Looks like I should do that.
I'm interested in the idea of measure from the ogive to the base of
the case--but how do you establish a datum line or point on the ogive?
I see nothing on these Sierras to use as a reference point.
I did experiment with a single-stage press, and I found that I still
got a range of .0045 from the shortest to the longest cartridge. So
the play isn't just in the Lee Classic press.
Flash
"Bob Bethune" <poi...@comcast.net> wrote in message
news:gun8oq$811$1...@news.albasani.net...
# I'm trying to keep my bullet seating to .001 of nominal. However
# bullet seating die I'm using will turn out several good ones in a row,
# and then suddenly push one 0.005 or more too deep, erratically and
# unpredictably.
#
# This is a Lee bullet seating die in a Lee Classic rotary press. There
# is play in the press. I suspect there is also play in the internals of
# the die.
#
# are there things I should investigate first?
#
#
For a meaningful answer, OP should note what caliber and what bullet he is
using. The Devil IS in the details, and these need to be considered.
He also shoud state the conditions of the non-standard loads- case,
procedure, etc, - if he is able to notice a difference between them and
the "standard" ones.
How 'bout it, Bob? Kick that ol' devil out here and let us see what is
going on.
Flash
Bill Smith
#
#I'm interested in the idea of measure from the ogive to the base of
#the case--but how do you establish a datum line or point on the ogive?
#I see nothing on these Sierras to use as a reference point.
http://www.sinclairintl.com/product/5582/Bullet-Comparators
This is what I use. Now that you've told us what kind of shooting
you're interested in, we can make some suggestions. Long distance
shooting requires a great deal of care when assembling you ammo (among
other things), even more care than short range, out to 300 yards,
benchrest requires.
there are some good books available here;
http://www.precisionshooting.com/books.html
Here you will find a wealth of information with an excellent forum on
F class as well as other long and short range disciplines.
http://www.benchrest.com/forums/
Bill Smith
wmar...@gmail.com
> ...
OK. To measure to the ogive, go to Sinclair International and get
some form of bullet comparator...
http://www.sinclairintl.com/prod_detail_list/Bullet-Comparators
You measure OAL with the bullet inserted in the comparator, and the
comparator will come with instructions for setting length so that the
bullet is a consistent distance from the lands..
However... As another has commented - once you're getting one
thousanth accuracy in your OAL, there are other factors that affect
accuracy. I understand that these include:
Case weight - as the outside dimension of the case is fixed, a lighter
or heavier case will hold more or less volume - i.e., the expansion
space for the initial ignition/acceleration is different.
Case neck thickness - they're rarely uniform, and need to be turned so
that there's fairly uniform thickness (i.e., less than 0.001"
and a big one - I've been led to understand by people who actually
have time to test their loads, is flash hole deburring - evidently
causing more consistent ignition.
Friends who shoot F-class and who also complain if they're out of the
"x" or "v" depending on the target in use, also swear by "Lapua" brand
cases, which, according to them, don't need case-neck turning, don't
need flash hole deburring, and do all weigh within about a grain of
each other.. They're more expensive, but these guys would rather
reload and shoot than tinker with their case-neck turning stuff...
HTH
Walter
John Smith
a bit. A Sinclair comparator rests on the ogive and gives you much more
repeatable measurements.
jumpin...@comcast.net
> ...
If your rifle and you are capable, you should have no trouble getting
sub MOA accuracy. By seating bullets to an OAL measurement you are
decreasing your chances. Get a bullet comparator that measures length
from cartridge base to the bullet ogive and you will eliminate any
adverse affects on accuracy created by varying bullet lengths.
Daniel
<poi...@comcast.net> wrote:
#In answer to some of the questions:
#
#I'm aiming for a high level of accuracy . . .
Hi, Bob,
I've been thinking about what could cause your variation in bullet
seating depth. I am assuming this is not a compressed-powder load.
Unless the case necks are very undersize after sizing (bullets make
terrible case neck expanders), I just don't think the friction/force
of the press or "play" in the press can be the real culprit because
the press always bottoms out on the positive stop of the die. The
"stop" position is going to be pretty damn repeatable even on a press
painted red instead of green or orange or blue.
Are you using the Lee bullet seating die with the floating inner
bullet aligning piece? The standard floating die unit in .308 is made
for FMJ's and contacts the bullet at a ring tangent to the ogive
somewhere below the bullet tip and above the surface that will engage
the lands of the bore. I'm thinking that any variation in the ogive
will make the Cartridge Overall Length vary. A custom-fit bullet
seating plug may be the answer. Lee used to offer to make one if you
send them a sample bullet. Or you can [have a friend] machine one. I
have used the trick of sticking a wad of aluminum foil into the bullet
seating plug and mashing a sample bullet into it -- it takes a while
to form the aluminum cap in the plug and you waste a few bullets in
the process, but the end result is seating with something more like
the tip of the bullet.
Accuracy is the goal and uniformity is the means. I wonder how it
would be possible to mic the finished cartridges from base to
"land-engagement diameter" of the bullet rather than the tip. The
reason I wonder is that it might be "jump to land" dimension that has
most effect on uniformity and accuracy at the firing range. Just
thinking out loud.
Good luck,
--
Daniel ( deltae...@usa.net )
Bob Bethune
Just for grins, I measured 20 bullets for overall length. Sierra
Matchkings, for .308 Winchester, 168 grain. Maximum spread 0.009.
Standard deviation 0.0025. I recently sorted a bunch of bullets by
weight; these 20 were all the same weight +/- 0.1 grain max. I would
think I would find even greater variation among bullets that haven't
been sorted by weight. In a sample of 35 Sierra Matchkings, all from
the same lot, I found a spread of 0.4 grain with a standard deviation
of 0.1 grain. Over a much, much larger sample--about 500 bullets--I
found a spread from 167.6 to 168.2 grains on nominal 168 grain bullets
from the same lot.
Larry The Snake Guy
# On Mon, 18 May 2009 11:48:11 +0000 (UTC), Bob Bethune
# Are you using the Lee bullet seating die with the floating inner
# bullet aligning piece? The standard floating die unit in .308 is made
# for FMJ's and contacts the bullet at a ring tangent to the ogive
# somewhere below the bullet tip and above the surface that will engage
# the lands of the bore.
That's what it's doing, and it's intentional because that is the most
critical part of the bullet to have in a repeatable place.
# I'm thinking that any variation in the ogive
# will make the Cartridge Overall Length vary.
Yes, but the ogive on good bullets is more consistent than the tip,
which is why having a consistent overall length is not particularly
important.
# I
# have used the trick of sticking a wad of aluminum foil into the bullet
# seating plug and mashing a sample bullet into it -- it takes a while
# to form the aluminum cap in the plug and you waste a few bullets in
# the process, but the end result is seating with something more like
# the tip of the bullet.
If this works, you are getting a consistent overall length which makes
your rounds appear more consistent when measured with a simple
caliper, but you're actually make the rounds effectively LESS
consistent. That's why bullet seating dies are not designed this way.
# Accuracy is the goal and uniformity is the means. I wonder how it
# would be possible to mic the finished cartridges from base to
# "land-engagement diameter" of the bullet rather than the tip.
There are gauges made to do exactly this.
# The
# reason I wonder is that it might be "jump to land" dimension that has
# most effect on uniformity and accuracy at the firing range. Just
# thinking out loud.
Yes, that is the exactly goal.
It's probably worth stating explicitly at this point in case it's not
obvious yet that the OP's rounds are most likely more consistent than
he thinks they are. Given the range of bullet lengths he just
reported, there's a good chance that most or all of the variation he's
seeing in his loaded rounds is due to inconsistencies in the bullet
tips. Getting a bullet gauge that measures on the ogive will allow him
to determine for sure how consistent the rounds are, but that's all.
Chances are they are already fine, and he just needs to set his die so
the average OAL is in the right range and not waste too many brain
cells worrying about trying to measure an exact length.
Unless of course, he has a heavy benchrest rifle and he's already
shooting 0.1 MOA and trying for 0.09 MOA...
Bob Holtzman
...........snip..........
# Chances are they are already fine, and he just needs to set his die so
# the average OAL is in the right range and not waste too many brain
# cells worrying about trying to measure an exact length.
#
# Unless of course, he has a heavy benchrest rifle and he's already
# shooting 0.1 MOA and trying for 0.09 MOA...
Consistancy is desireable of course but if he is shooting around
..50-.75 MOA he will benefit from playing with seating depth, from
..030 jump to .010 jam. There are inexpensive tools to achieve just
this. Try the Sinclair catalogue.
--
Bob Holtzman
AF9D 8760 0CFA F95A 6C77 E125 BF90 580F 8D54 9279
"If you think you're getting free lunch,
check the price of the beer"
Bob Bethune
Just for grins - haven't had a chance to buy one of those Sinclair
gauges yet - I simply took the floating part of the bullet seating die
out of the die and used it the same way you would use the Sinclair
gauge. Indeed, most of the variation in bullet length disappeared.
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chuck
@news.albasani.net:
> ...
You might want to consider where the sources of variability are in the
press and address those by installing bushings in place of simple
drilled holes. Once you have bushings installed, replace the bolts used
as pivot pins with hardened bolts with known diameters that complement
the bushings that they will be installed in.
Then address the die variables in a systematic manner...
cheers,
chuck...
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