View Full Version : what happened here???
greetings from Italy guys, Andy here
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.
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Looks like a very spicy round, was it a reload?
I'm not entirely sure from the pictures, are the rear of bolt lugs on either side of the extractor mushroomed or smashed down?
Help us out bro. Give us details. What kind of ammo, etc...
ICANHITHIMMAN
03-27-13, 15:13
Way over pressure replace bolt and like the others said we need the details either someone used the wrong powder of the manufacture did.
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
Andy,
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.
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.
first thing I thought about was bullet setback...
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.
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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.
Primer in the face; were you shooting left handed?
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-
1) Too much powder.
2) Neck too long. The neck gets pinched, holding the bullet too tightly causing chamber pressures rise too high before the bullet moves
3) 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.
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-
1) Too much powder.
2) Neck too long. The neck gets pinched, holding the bullet too tightly causing chamber pressures rise too high before the bullet moves
3) 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
Your wrong on most of what you just said!!!!!!!!!!!!!!!!
Yep... the neck would have to be ridiculously long to cause a crimping issue in most factory chambers.
And a bullet long enough to jam in the lands wouldn't fit in the Mag in the first place.
I just have to think this was a simple over charge of powder.
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. Mark, you missed that it was a reload.
G Woody, care to elaborate?
Mark, you missed that it was a reload.
G Woody, care to elaborate?
Seating depth does matter. Seating too deep & pressure will rise. In effect you have created a smaller case, thus raising pressure. The bullet seated to jam, that is touching the leade and or rifling isn't a big deal. Benchrest shooters do it all the time, and as someone else said, the round would be too long to fit the magazine. It's possible the case had grown without being trimmed, thus being pinched. Most chambers have some extra neck length built in. Most like a very heavy overload, or the wrong powder. Shooting someone else's reloads are always risky. Many years ago I purchased reloads because they were cheap, and I didn't know crap. I still don't know it all but I never shoot someone else's reloads unless I've seen then operate at a reloading bench. A progressive reloading machine is much more likely to bridge, give you a light load, then, an overload on the next charge. I use a Harrell's Precision powder measure and when I have a loadind block full of charged cases I look into all of them with a flashlight.
Mark, you missed that it was a reload.
G Woody, care to elaborate?
Ok.. I still believe it to be a powder overcharge... :confused:
I don't disagree with anything you said.
However, a round with lose neck tension, that gets the bullet set back, usually will not spike pressures enough to matter. Now, seating the bullet and crimping it too deep, that's another story. I believe that's what Mistwolf was getting at.
Ok.. I still believe it to be a powder overcharge... :confused:
I do also.
BTW, setback is a whole different animal with pistol ammo and faster powders. I've seen tests on this. I haven't seen tests for rifles and would love to see one.
BTW, setback is a whole different animal with pistol ammo and faster powders. I've seen tests on this. I haven't seen tests for rifles and would love to see one.
I totally agree, In a straight case the available power & burn space decreased very rapidly with overly deep seating of the bullet.
Suwannee Tim
03-28-13, 16:05
Seating depth does matter. Seating too deep & pressure will rise.......
Deeper seating causes lower pressure, not higher, this is a fact not an opinion. No change is seating depth will cause a safe load to operate at this pressure. Seating depth changes cause marginal pressure changes, not drastic pressure changes. This cartridge was loaded with too much powder or the wrong powder.
Deeper seating causes lower pressure, not higher, this is a fact not an opinion. No change is seating depth will cause a safe load to operate at this pressure. Seating depth changes cause marginal pressure changes, not drastic pressure changes. This cartridge was loaded with too much powder or the wrong powder.
You may get someone hurt. Seating depth didn't cause this incident, but it damm sure will in a handgun. Stating you declaration as a fact is foolish and ill advised!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Suwannee Tim
03-28-13, 16:54
You may get someone hurt. Seating depth didn't cause this incident, but it damm sure will in a handgun. Stating you declaration as a fact is foolish and ill advised!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
You are correct, deeper seating in a handgun cartridge can cause higher pressure. We are however talking about rifles here!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ICANHITHIMMAN
03-28-13, 17:14
I wonder what the chamber is?
Seating depth does matter. Seating too deep & pressure will rise. In effect you have created a smaller case, thus raising pressure...
It reduces case space temporarily. But the neck tension is not enough to hold the bullet tightly enough to keep it from moving and cause such pressures. In fact, the pressure from the primer alone is enough to drive the bullet out of the neck and jam it in the rifling. Case volume with the bullet seated is not the actual working volume.
The bullet seated to jam, that is touching the leade and or rifling isn't a big deal. Benchrest shooters do it all the time, and as someone else said, the round would be too long to fit the magazine...
What you are forgetting is that benchrest shooters lower the powder charge according to the increase of pressure. Do you know why Roy Weatherby used long leades in his rifles? To obtain the extra velocities promised in his proprietary cartridges. The extra jump actually increases case capacity so more powder can be used. Actual case capacity isn't the internal volume of the case with the bullet seated, it's the volume inside the chamber when the bullet hits the rifling.
This is why 5.56 NATO spec ammo gives signs of high pressure in true SAAMI spec 223 chambers. The leade of the 5.56 chamber is longer, allowing the bullet a longer jump. More powder can be used to generate higher velocities while keeping pressures to safe levels. It's not that 223 ammo is loaded to lower pressures, it's loaded to make it's design pressure in chambers with short leades.
Tight necks do increase pressure. P.O. Ackley performed tests firing .311 and .323 diameter bullets in .308 diameter barrels. He found that firing the larger bullet in the smaller bore produced no real increase in pressure. The bullet simply swaged to the smaller diameter and went about it's business. What increased pressure dramatically was forcing a case loaded with a .323 bullet into a chamber with the neck cut for a .308 diameter bullet. The tight neck & throat increased the pressure needed to get the bullet moving. When he opened the neck of the chamber to the proper diameter for a .323 bullet, pressures were normal.
Maybe the case neck would have to be real long to be a factor in a 5.56 chamber, a 223 Wilde chamber or modern sporting 223 chamber (not true SAAMI), it will be a factor in a true 223 chamber and the chambers of many other calibers. I know neck length was a factor when I was reloading for my 6mm Remington.
While a round with the bullet seated out too deeply may not fit in the magazine, a case with low neck tension will jam a bullet into the rifling when chambered by a self loading firearm (or in a manually operated action worked quickly). When the brass stops in the chamber, momentum will carry the bullet forward until it's stopped by the rifling. Now, pressures will rise too rapidly before the jammed bullet gets moving. This is one reason why a proper crimp is so important when reloading ammo for self loading pistols which use thin wall cases and heavy bullets.
As far as what affect seating depth has on pressure, yes, we are talking about rifle ammo. Pistol ammo using fast burning powders can change the rules. But, in large cases using fast burning powders that give low loading densities, fillers are often used to fill the unused case space without catastrophic results.
ARs are not some magical rifle that defies the laws of physics. What causes over pressure in other rifles also causes over pressure in ARs.
I strongly recommend reading P.O. Ackley's Handbook for Shooters & Reloaders, especially Volume 1. Volume 2 also is a gold mine of information, but mostly consists of loading data of a myriad of wildcat cartridges developed during that time and the reloading data is unfortunately out of date
It reduces case space temporarily. But the neck tension is not enough to hold the bullet tightly enough to keep it from moving and cause such pressures. In fact, the pressure from the primer alone is enough to drive the bullet out of the neck and jam it in the rifling. Case volume with the bullet seated is not the actual working volume.
What you are forgetting is that benchrest shooters lower the powder charge according to the increase of pressure. Do you know why Roy Weatherby used long leades in his rifles? To obtain the extra velocities promised in his proprietary cartridges. The extra jump actually increases case capacity so more powder can be used. Actual case capacity isn't the internal volume of the case with the bullet seated, it's the volume inside the chamber when the bullet hits the rifling.
This is why 5.56 NATO spec ammo gives signs of high pressure in true SAAMI spec 223 chambers. The leade of the 5.56 chamber is longer, allowing the bullet a longer jump. More powder can be used to generate higher velocities while keeping pressures to safe levels. It's not that 223 ammo is loaded to lower pressures, it's loaded to make it's design pressure in chambers with short leades.
Tight necks do increase pressure. P.O. Ackley performed tests firing .311 and .323 diameter bullets in .308 diameter barrels. He found that firing the larger bullet in the smaller bore produced no real increase in pressure. The bullet simply swaged to the smaller diameter and went about it's business. What increased pressure dramatically was forcing a case loaded with a .323 bullet into a chamber with the neck cut for a .308 diameter bullet. The tight neck & throat increased the pressure needed to get the bullet moving. When he opened the neck of the chamber to the proper diameter for a .323 bullet, pressures were normal.
Maybe the case neck would have to be real long to be a factor in a 5.56 chamber, a 223 Wilde chamber or modern sporting 223 chamber (not true SAAMI), it will be a factor in a true 223 chamber and the chambers of many other calibers. I know neck length was a factor when I was reloading for my 6mm Remington.
While a round with the bullet seated out too deeply may not fit in the magazine, a case with low neck tension will jam a bullet into the rifling when chambered by a self loading firearm (or in a manually operated action worked quickly). When the brass stops in the chamber, momentum will carry the bullet forward until it's stopped by the rifling. Now, pressures will rise too rapidly before the jammed bullet gets moving. This is one reason why a proper crimp is so important when reloading ammo for self loading pistols which use thin wall cases and heavy bullets.
As far as what affect seating depth has on pressure, yes, we are talking about rifle ammo. Pistol ammo using fast burning powders can change the rules. But, in large cases using fast burning powders that give low loading densities, fillers are often used to fill the unused case space without catastrophic results.
ARs are not some magical rifle that defies the laws of physics. What causes over pressure in other rifles also causes over pressure in ARs.
I strongly recommend reading P.O. Ackley's Handbook for Shooters & Reloaders, especially Volume 1. Volume 2 also is a gold mine of information, but mostly consists of loading data of a myriad of wildcat cartridges developed during that time and the reloading data is unfortunately out of date
I have Ackley's books. He did advance case design. I've owned and reloaded Wby's, 7mm & 300, and shot most of the others, 378, 460 etc. His freebore decreased accuracy. I had to use up most of that freebore to get good accuracy. Of course the rounds would not work thru the magazine then. As to Ackley loading oversized bullets into the lead that just isn't germane to this discussion. As an aside, I've loaded 17 rem. to .458 win mag. and the .17 rem is by far the most touchy to deal with. That's the only time I've had a primer fall out when I opened the action. Have a nice Easter:smile:
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