Case detonation fact or myth?
Ken and Clara
never known someone with personal experience.
I have loaded some 7.62x54R with half charges for my little grandson to
shoot in his M44 Mosin Nagant. I would like to know if case detonation is a
possibility and is it real or a suburban legend. Thanks gents.
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Douglas A. Gwyn
# I have heard of case detonation from small powder charges in rifle cases
That wouldn't make any sense. Detonation occurs when a state
change (such as chemical change) propagates through a material
at a rate faster than the speed of sound in that material.
How would the case be changing? I think this must be referring
to case *rupture*, quite a different phenomenon. A case might
conceivably rupture if not enough pressure is generated to push
the bullet down the barrel (there *is* resistance) nor cycle
any autoloading mechanism. More likely such a "squib" load
results in the bullet getting stuck in the barrel and the *next*,
full-power load results in case rupture.
Clark Magnuson
H110 in 44 mag and 357 mag. I have been told the only risk there is a
stuck bullet.
In the February "Handloader" magazine, John Haviland's article on
reduced loads quotes Ron Rieber of Hodgdon as saying that there is a
problem with reduced loads in cartridges with large powder capacities
compared to their bore. The powder partially ignites sending the bullet
into the bore and then lodging and stopping. The charge then fully
ignites causing a pressure spike. He has been unable to reproduce this
phenomena in the lab with a new barrel, however, in a rough throated
..243 with a slow burning powder and reduced charge can make a pressure
spike that will lock the bolt shut.
As a matter of safety, I pull down any handloaded ammo that I get from
anyone else. The only exception is if I trust the loader and I know
explicitly what I am getting.
bwatson
I am not sure if it is a legend or not but why risk it if there is an
alternative.
You don't mention the powder you are using but let me recommend Accurate Arms
5744.
It is especially formulated for reduced loads and is not position sensitive in
larger cases.
I load it extensively in .303,30-06,45/70 and 7.62X54R.
If you are interested I can provide you load information. I have an M39 (Finnish
Mosin Nagant) that shoots 1" groups at 100yds using a reduced load w/ cast
bullets. Velocity runs about 1600 fps.
BTW-did you know that the M44 was designed to be fired with the bayonet
extended. I have shot these rifles folded and extended and been amazed at the
difference.
Hope this helps,
Bill
Ken and Clara wrote:
> ...
--
Please let me know if I may assist you further.
Bill Watson (bs-w...@tamu.edu) - Communications Specialist
Texas Agricultural Extension Service - 107I Reed McDonald Bldg. - TAMU
College Station, Texas 77843-2112 - (979) 845-2807 (979) 862-1202
Agricultural Communications - http://agpublications.tamu.edu
KYRIEELLIS
#I have heard of case detonation from small powder charges in rifle cases but
#never known someone with personal experience.
#I have loaded some 7.62x54R with half charges for my little grandson to
#shoot in his M44 Mosin Nagant. I would like to know if case detonation is a
#possibility and is it real or a suburban legend. Thanks gents.
It does happen, and is not limited to small charges of slow propellants.
Happily, it's fairly rare. Unhappily, what causes it is not well understood. If
you would like, I can send along some photos of a Model 1896 Swede Mauser that
was destroyed by this odd phenomenon.
The bottom line is I'd strongly suggest not throwing charges that are under
loading manual minimum listed charges.
Hope this helps!
Best regards,
Kyrie
Ken Marsh
Powder transcending the deflagration rate into the detonation rate is
primarily a phenomenon of small charges of slow, powders in large
capacity cases. The likelyhood is much greater if the powder is located
far away from the primer.
I posted an article on the theory behind this a few months ago, you
can probably find it on Deja News:
The topic was hotly debated in the 60's but is commonly accepted now. I
think the Hogdgon company is the only holdout. Nonetheless, many of
their magnum pistol loads bear the caveat "do not reduce".
I have no doubt about it at all, having reduced the data and seen the
graphed pressure curves roll up and down the chamber and peak when
meeting. Due to our safety protocol we had to retire several tubes due
to excessive pressures caused by this phenomenon.
Your half-charges should be safe enough if you have used a powder like
4895 of faster. Accurate Arms bottles a powder called XMR-5744 that is
designed for safe reduced charges in large capacity cases like .50-70.
Ken.
Ken and Clara <kru...@megabits.net> wrote:
#I have heard of case detonation from small powder charges in rifle cases but
#never known someone with personal experience.
#I have loaded some 7.62x54R with half charges for my little grandson to
#shoot in his M44 Mosin Nagant. I would like to know if case detonation is a
#possibility and is it real or a suburban legend. Thanks gents.
--
-------------------------------------------------------------------------
Mail: kmarsh at charm dot net | Using a computer should not
WWW: http://www.charm.net/~kmarsh | be a test of manual dexterity.
-------------------------------------------------------------------------
flimflam
aware of Winchester 296 pistol powder.
It is also used in some rifle cartridges, such as .30 Carbine, as well as
7.62x39. Use the charges as listed in the manual, and do not ever "down
load" 296. Detonation is a very real thing, and one surely wouldn't want to
duplicate it. But, as has been stated, it is a little known science to most
reloaders, and is best left that way. Downloaded charges of 296-- below 90%
case capacity are usually the culprit. Otherwise, I find 296 to be one of
the best, if not the best powder for all my magnum pistol needs.
--
Flimflam
A-1 Pawn & Jewelry
1925 S.E.Hwy 19
Crystal River, Florida, 34429
352-795-2777
fax: 352-795-2093
flim...@xtalwind.net
URL: http://members3.clubphoto.com/jdavid270383
##I have heard of case detonation from small powder charges in rifle cases
but
##never known someone with personal experience.
FBC3
#shoot in his M44 Mosin Nagant.
"Detonation" has been caused by handloaders accidentally throwing more than one
powder charge into a case, a good reason to use loads that will overflow if
charged twice. Not sure what you mean by "half charges"; be careful not to
stick a bullet in the barrel and then fire another into it. For light loads,
best to use cast bullet data from the Lyman manual. You can shoot jacketed
bullets instead of cast. Fred
Robert Grizzard
# never known someone with personal experience.
# I have loaded some 7.62x54R with half charges for my little grandson to
# shoot in his M44 Mosin Nagant. I would like to know if case detonation is a
# possibility and is it real or a suburban legend. Thanks gents.
Ackley wrote of it, and several years ago _Handloader (IIRC) had a picture
of a T/C Contender that blew up from a light charge of a *coated* powder.
I emphasized "coated" for a reason. In the research I have done on the
literature related to the phenomenon, that seems to be the common factor.
Practically speaking, something like SR 4759, 4227, 3031 or 4895 would be a
lot better choice for reduced loads in a bottleneck rifle case than
something like 4350, 4831 or one of the ball powders. I personally like
4759 for reduced 223 loads.
Ron Seiden
having the kid find out the answer, it also helps accuracy to have the case
more full.
Tom Currie
#
# never known someone with personal experience.
Despite the couple of people who explained why "detonation" is
"impossible", the simple fact is that instances of VERY excessive
pressure have been observed and documented in significantly under-loaded
cases.
There is not any 100% proof (that I am aware of) concerning the exact
process by which such instances occur, but there is one leading theory
that has been tested and reliably reported in gun journals.
That theory suggests that excessive pressure is likely to occur when the
powder charge fills less than half the case volume.
Remember that powder in a cartridge case does NOT explode all at once,
it burns. And that burning occurs starting from the primer and
proceeding through the charge (albeit very quickly). The theory is that
if the powder fills less than half the case AND the round is handled in
such a way that the powder is distributed away from the primer and lying
mostly along what is otherwise considered the wall of the case, this
exposes a MUCH larger surface area to ignition by the primer and causes
the powder charge to burn more quickly. Not faster, just more quickly.
I'm sure you realize the burning rate of the powder is fixed by its
chemical composition and physical characteristics (generally the surface
area of each grain of powder) -- THAT doesn't change. But think about
the overall charge as a cylinder burning at 4000 fps from one end versus
the same volume as a half cylinder burning at the same 4000 fps having
been ignited all along the flat side. Both produce the exact same total
amount of propellant gasses, but the half cylinder burns through more
quickly and produces that volume of gas sooner. Instead of the normal
buildup of pressure which shoves the bullet forward and accelerates it
up the barrel with a constantly expanding volume, you get a sudden spike
of pressure contained within the initial case volume before the bullet
has time to get moving.
I don't recall the name of the writer or the magazine (probably Guns &
Ammo), but a few years ago they did an article about this theory and did
some pressure tests with partial loads. During some of the tests,
lightly loaded rounds were first turned base down to move the charge
against the primer immediately before being turned to firing position
and none exhibited excessive pressure. Other rounds with the same light
load were turned bullet down to move the whole charge forward, then
turned to firing position; some of these rounds showed elevated
pressures. Another batch of rounds with the same light load were
positioned horizontally and the barrel tapped to try to level the charge
along the case wall immediately before firing; some of these rounds
showed normal to slightly elevated pressures but some showed
significantly elevated pressures.
As I recall, the same tests were repeated with charges intended to
represent the same power level but using a powder that took up more case
volume and all showed normal pressures. There was some talk about using
filler along with the powder but I don't remember if they tried anything
like that or just talked about some reason you shouldn't do it. Their
bottom line recommendation was to pick a powder that would give the
desired power level while filling at least more than half the available
case volume.
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Isaac B Wilder
: never known someone with personal experience.
: I have loaded some 7.62x54R with half charges for my little grandson to
: shoot in his M44 Mosin Nagant. I would like to know if case detonation is a
: possibility and is it real or a suburban legend. Thanks gents.
This has been written about for years. The supposed cause is rapid burning of a reduced
charge of slow burning (H-4831) powder. Supposedly the small amount of powder is exposed
to more of the primer flash causing more rapid burning than would be expected. Most
manuals tell you not to reduce loads below 10% for these types of powders. IT ISN'T A
LEGEND. If you wan't to produce reduced loads use afast or medium rate powder. Check
under cast bullet loads for appropriate loads as well. I hope this helps.
--
Isaac(Ike) B. Wilder
That's my story and I'm sticking to it.
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Bruce Barr
primer as the case lays on its side in the chamber. I've read
articles of it happening at times over the years. It's why a filler
is used to keep the powder in contact with the primer.
Bruce Barr
NRA Life
USPSA Life
On 25 Jan 2001 15:59:15 -0500, "Ken and Clara" <kru...@megabits.net>
wrote:
> ...
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Robert F Wieland
types use that term for a particular type of explosive reaction, in which
the flame front moves through the explosive as a shock wave, faster than
the speed of sound.
What I think you are talking about went around in the 1950s & 1960s. A
number of rifles were blown up, obviously in "overpressure" mode, by
handloads using reduced charges of slow-burning powders. Last I heard,
nobody trying to reproduce this on purpose was able to destroy a rifle,
but enough wrecked rifles were generated that there was no doubt the
effect was real. The things that seemed to run through all were
slow-burning powders in charges that did not come close to filling the
case. Even today you will hear theories about how it happens. Once it
became well-known that slow powder should not be used for reduced loads,
it stopped happening.
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Clark Magnuson
Western Powder
http://www.westernpowders.com/
Hodgdon, the seller of H110 tells me the only danger with reduced loads of H110
is stuck bullets.
Before I found this out, I tested 22 gr H110 and 125 gr FMJ in a 357 mag by
pulling a trigger string. Now I have downloaded and tested with lead bullets.
Clark
flimflam wrote:
> ...
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