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! 
http://www.combatshootingandtactics.com/news.htm
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?
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 pressureā¦IE kaboom.
This is why its not a good idea to shoot bullets with large āhollow pointsā in ARās. I once bought a box of 45 grain JHPās and within the first mag 3 rounds got pushed back into the case. Luckily I caught it, and disposed of the rounds.
The bullet being āset backā 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.
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 Iāll compare OAL.
The situation causes pressure spikes and no es bueno.
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.
Ha beat you allā¦
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 donāt 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.
Iāve 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 donāt 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 .
I doubt it. My money is on case failure.
In any event, what in the hell were they doing shooting bolt gun ammunition in an auto-loading rifle?
I think this more on the line of bad brass/ insufficient crimp! I had this problem with Rem brass reloading it where it will not have sufficient tension to stop bullet from set back ! I found I had to anneal the brass and resize to get it to function as it should! A properly sized/tensioned case neck will not allow bullet set back! With a good crimp is added protection from such! Iāve never had bullet set back in any of my semiās that -cause my reloads are properly neck tensioned an crimped!
Yeah, due to excessive pressure due to setback. Did you see the picture of another round (presumably from the gun?) Bullet is set way back.
In any event, what in the hell were they doing shooting bolt gun ammunition in an auto-loading rifle?
I believe this is the same ammo from Remingtonās recall notice from March 14th.
Thanks Oscar, I did not find that thread.(I blame the pain killers!)
Mods, thanks for moving, I didnāt think about ammo thread.
Niether did the operator of that RRA carbine. :eek:
Iāve seen the upper blow out like that once, and it was with an army colt m4, but never seen the carrier blow out like that. Crazy, luckily that guy wasnt hurt.
Pushing the bullet back might cause an increase in pressure, but thatās mitigated by the fact it creates more freebore- that is, the distance the bullet must jump before it engages the rifling. This reduces pressures. Itās been found that compressing loads by seating the bullets a bit deeper doesnāt have that much effect on pressures.
While itās certainly possible the bullet was seated deeper when loaded into the chamber, itās doubtful (although not impossible) that it would result in catastrophic pressures. The cartridge shown in the picture shows signs of having been in the magazine when the rifle came apart. The tip is flattened from being slammed against something and there is a dent in the shoulder. Itās also looks to be crimped. It took some force to push that bullet deeper into the case. If that came from simply chambering the round, the rifle has serious feed problems.
It does not matter this was ābolt actionā ammo. For one, it isnāt. Itās 223 Remington, loaded to fit 223 spec barrels with the shorter leade and safe to fire in 223s and 5.56 rifles of any modern action type.
The excessive pressure could be the result of a tight throat, bullet seated too far out for the leade, too much powder, obstruction in the barrel, too hot a primer or a combination thereof. Itās possible itās from the bullet being seated too deeply, but very doubtful
My intent was not to debate the 223 vs. 5.56 chamber or the interchangeability of the ammunition between the two.
Match ammunition is for bolt action rifles and race guns. The use of ammunition without cannelured bullets and roll crimps in an auto-loading fighting rifle poignantly illustrates bad judgement.
Iāve got my serving of crow ready IF that ammunition is cannelured/crimped, but I doubt it.
I agree with your second point. I have to wonder if that ammo was loaded with the wrong type of powder (is that possible?) or was it overloaded?
I wonder if Remington is going to replace that weapon?