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Mac5.56
05-30-10, 12:46
Was at the range the other day with a friend who is training me (two tour Iraq vet, spent his last years in the service training recruits on the M4 at West Point). I've been periodically mixing in some Romanian bulk 5.56 in with the other ammo I am using. (you can find images of the ammo, and a description of the issues with it here: http://m4carbine.net/showthread.php?p=669361#post669361 )

Anyway, I had two repeated failures to extract with this ammo that resulted in the second round slamming into the ripped cartridge stuck in the chamber. After we dropped the magazine after both failures we examined the rounds that had pushed into cartridge. The bullets were both jammed pretty far into the casings and pushed at a slight angle.

He told me they could have "backfired" due to the pressure placed on the powder by the bullet being slammed back into the casing? It makes sense to me that this could happen, however I have never heard of it. So I figured I would go to the best source of M4 knowledge I know of and see what your thoughts are:

Myth/Tall Tail or Fact?
kry226
05-30-10, 13:12
Never heard of backfire, but if it is a possibility, I am not sure it would be caused by the condition you described. I do know that just about any reloading book will tell you that some bullets are seated against the powder in some cases, creating a certain amount of powder compression, when loaded. The only warning Lyman's 49th gives from excessive compression is that the cartridge OAL will continue to increase after removing it from the die, which could lead to problems.

I'd be interested to hear what others have to say. Might want to post this in the reloading forum too.
Molon
05-30-10, 13:24
http://www.box.net/shared/static/1df2jm6lt9.gif

http://www.box.net/shared/static/1df2jm6lt9.gif

http://www.box.net/shared/static/1df2jm6lt9.gif

http://www.box.net/shared/static/1df2jm6lt9.gif
CAVDOC
05-30-10, 13:28
pure bs. smokeless powder is a flammable solid and not subject to detonation purely from shock/vibration. It requires a heat source or spark to set it off. A bullet pushing into the case against powder will not cause ignition. Many loads in current reloading manuals call for a compressed charge of powder.
Mac5.56
05-30-10, 13:36
pure bs. smokeless powder is a flammable solid and not subject to detonation purely from shock/vibration. It requires a heat source or spark to set it off. A bullet pushing into the case against powder will not cause ignition. Many loads in current reloading manuals call for a compressed charge of powder.

Thank you for taking the time to explain to me why this was a myth. While the emoticons saying BS are great, they didn't help me much... :)

If there is one thing I have learned about guns and ammo in the last two years since I have decided to become a weekly shooter, and part of the sport, it is that for every 1 fact there are about 20 myths. I've also found that a large majority of them come from LE and Military people I meet which baffles my noggin.
OMD
05-30-10, 13:37
That does sound like the most uninformed thing one could possibly say.
arizonaranchman
05-30-10, 15:01
Yeah that's BS. Some loads are compressed fairly heavily in fact. This would not cause a powder to ignite.
TOrrock
05-30-10, 15:56
No, it wouldn't have "backfired", but you will increase the pressure level and it is possible to have very bad results.

I'd toss that ammo.
Mac5.56
05-30-10, 23:10
The ammo is tossed. I have twenty rounds of the bulk left, that I may shoot one at a time after I install my Hbuffer to see if the failure repeats but I'm leaning more towards getting rid of those as well.