i need to share with us my experience with an ar15. not my rifle…
i have an idea on what happened but i wish to know your opinions.
after i pulled the trigger, i got piece of primer on my face, a hard recoil and when i found the brass i saw this.
well… yes the bolt lugs are worn.
the brass is reloaded… i cannot give reload details cause we use different powder here in italy.
i think the brass was overpressured, and the worn lugs on the bolt permit the bolt to leave the barrel extension so it could explain the brass in the pic #1
am i wrong?
This is only a guess…
From the obvious markings of the ejector and extractor on the back of the case and the “belting” around the end, could the round not have been completely seated in the chamber upon firing?
well if the bolt is not completly closed, the firing pin should not be able to strike the primer, i think. i cannot understand if the barrel extension have lost the bolt lugs or if the brass was not completly in the chamber
It looks like the cartridge was fired with a very high pressure load.
The marks on the case head show where the brass flowed into the ejector hole and in the crease between the bolt head and extractor. The brass approximately 10mm above the extractor groove is also raised, probably from the brass still obturated to the chamber walls while the high-pressure gases started the carrier’s initial rearward movement during the unlock phase. The primer did its job as best it could holding in the chamber pressures, but gave way.
The bolt lugs held but were galled and must be inspected for cracks if you intend to use it again.
What powder was it? Unless it was made in Eastern Europe there are only a few powder manufacturers in Western Europe. Fiocchi brass is usually very good.
well the powdes is a PEFL 19 made here in italy from Baschieri and Pellagri
for the 55gr fmj bullet it say 26 to 27.5 gr
the reload was made at 26.5 gr
Andy, if you were using standard 55 grain bullets my guess is your case neck tension may not have been tight enough or you did not have a crimp on the bullet.
Was your brass trimmed to length? If the neck was too long it could have held the bullet very tightly and raised internal pressure.
If the bullet was pushed back into the case when it chambered, when you pulled the trigger it would have raised internal pressures higher than the CIP-rated 4300 bar. – which would have caused the brass and primer to fail.
Like most others have said, the signs all indicate over pressure whether from an overload or bullet setback. I’d replace the bolt were it me & would be very dubious of shooting more from this particular batch of ammo. FWIW, I reload but I don’t shoot reloads done by others.
oh no no. this is not my rifle…and nor my ammo.
it’s my friend’s rifle…
he told me yesterday he had some trouble and so i tested…and got this result…
what will be the max pressure in bar for a .223?
62 grain military FMJ (5.56mm NATO M855) = 3792 bar. working pressure (not max)
55 grain military FMJ (5.56mm M193) = 3585 bar. working pressure (not max)
5.56mm maximum working pressure 62,350 psi = 4300 bar.
Proof load (5.56mm High Pressure Test M197, 56 grain bullet) = 4826 bar.
No, not bullet set back. Bullet setback increases bullet jump and if anything, results in a drop in pressure.
That case, as pointed out by Sinister, shows signs of extreme over pressure. It could very well have resulted in a ka-boom. The over-pressure could result from any and all of the following conditions-
Too much powder.
Neck too long. The neck gets pinched, holding the bullet too tightly causing chamber pressures rise too high before the bullet moves
Bullet seated out too far. When the bullet is seated out too far, it can be jammed into the rifling. Again, pressure rise to dangerous levels because the bullet doesn’t move soon enough.
The only way loose neck tension could cause this kind of pressure is if the bullet jumps forward into the rifling when it’s chambered with the same result as having the bullet seated out too far.
The “belt” looks like case head separation was eminent. The brass may have been reloaded one too many times. (this by itself will not cause over-pressure or signs of over-pressure.)
The brass flowed back into the extractor and the ejector and the head expanded to the point the primer fell out. All in all, it’s lucky it was not worse
Overcharge on that Fiochi ammo. Fiochi is usually pretty decent stuff. They can’t seem to center up their flash holes in the primer pocket, but I don’t read of them Kabooming or nearly Kabooming guns.
I’d just chalk it up to a fluke and move on. I’ve had this happen with Remington ammo before too.
