Warning @ Remington ammo

[ScottFarkus]

Hello to all. Paul Howe has pics of a Kaboomed RRA on the CSAT site.
Go to news tab on right. It seems to involve Rem Premier match 62gr. Product # R223R6.
Wow! Chech out that bolt carrier.

I am home recuperating from shoulder surgery (slap tear) and am working on my left handed hunt-and-peck!

[chadbag]

http://www.combatshootingandtactics.com/news.htm

Bullet setback

[Mac5.56]

Bullet setback

Pardon my ignorance but what does that mean?

I had a two failures to extract with surplus Romanian 5.56 where the round pulled from the magazine and jammed up against the stuck round looked exactly like the Remington round in the last photo on that post. But I have never heard of Bullet Setback. What is it?

[Belmont31R]

The bullet catches on something, and is pushed back into the case. Can cause dramatic pressure increases when fired. The powder needs a certain amount of room to maintain a safe pressure within the case. When the bullet is pushed back into the case it can compact the powder causing high pressure....IE kaboom.




This is why its not a good idea to shoot bullets with large "hollow points" in AR's. I once bought a box of 45 grain JHP's and within the first mag 3 rounds got pushed back into the case. Luckily I caught it, and disposed of the rounds.

[chadbag]

Pardon my ignorance but what does that mean?

I had a two failures to extract with surplus Romanian 5.56 where the round pulled from the magazine and jammed up against the stuck round looked exactly like the Remington round in the last photo on that post. But I have never heard of Bullet Setback. What is it?

The bullet being "set back" in the case. In your case, the new round ran into the stuck round and caused it. In a case like this, the round is stripped from the mag and as itbruns up the feed ramps it is set back by the pressure on the bullet from the ride up the feed ramps.

This is due to insufficient neck tension. This is why most rounds for auto loaders are crimped.

[Artos]

Pardon my ignorance but what does that mean?

I had a two failures to extract with surplus Romanian 5.56 where the round pulled from the magazine and jammed up against the stuck round looked exactly like the Remington round in the last photo on that post. But I have never heard of Bullet Setback. What is it?

basically the projectile gets pushed back into the case due to the pressure of chambering the round (you should avoid loading the same bullet over and over on any of your automatics)

I hand load and buy factory both and have never encountered one as I'll compare OAL.

The situation causes pressure spikes and no es bueno.

[tb-av]

It means the bullet is set too deep in the case creating too much pressure. Can be caused by repeatedly clambering a round.

Or maybe in this case the bullet is simply not tight enough in the case and gets pushed too deep in the case on initial feeding into the chamber.

EDIT: sorry everyone posting at same time.

[Belmont31R]

Ha beat you all...

[Mac5.56]

The bullet being "set back" in the case. In your case, the new round ran into the stuck round and caused it. In a case like this, the round is stripped from the mag and as itbruns up the feed ramps it is set back by the pressure on the bullet from the ride up the feed ramps.

This is due to insufficient neck tension. This is why most rounds for auto loaders are crimped.

Thanks Belmont and Chadbag,

When it happened to me, the guy I was shooting with was a two tour vet, and he told me of the dangers, but I don't think he completely understood why the explosion would happen. He thought it was the impact of the bullet against the powder. However it seems that the problem would occur when the user tried to fire the compressed round. That makes a lot of sense to me.

So, what rounds have you all seen this happen with? I guess we can add the crappy Romanian ammo that I reported problems with a year ago. Any others?

edited to add: Thanks to the others as well! Right on! I learn something new everyday.

[FromMyColdDeadHand]

The bullet catches on something, and is pushed back into the case. Can cause dramatic pressure increases when fired. The powder needs a certain amount of room to maintain a safe pressure within the case. When the bullet is pushed back into the case it can compact the powder causing high pressure....IE kaboom.




This is why its not a good idea to shoot bullets with large "hollow points" in AR's. I once bought a box of 45 grain JHP's and within the first mag 3 rounds got pushed back into the case. Luckily I caught it, and disposed of the rounds.

I've seen it happen with .308 ammo in an AR10/SR25 platform. Since 308 ammo has been used almost exclusivly in bolt guns till the last few years, or the AR10 around ran MIL or handloads, I don't think it was seen much. I think the neck tension was not as tight as with 556 ammo for commercial loadings, so there could be set back as the round fed into the chamber- M4 cuts or not. I was told that you could feel it as a hiccup in the bolt going forward .