Crazy kaboom

[gew98]

http://www.falfiles.com/forums/showthread.php?p=4052241&posted=1#post4052241



Oi !. Lucky bugger did not even get cut up !.

[Char-Gar]

This is his story;

"My kaboom was with rifle I built with known parts and ammo I loaded. So unless this is a total fluke have no idea. No way any cases got overcharged and pulled down many remaining to verify charge was correct. No sign of obstructed bore, no powder mixup, correct bullets, BCG and gas system had run ~500 rounds flawlessly since built and seemed perfect. Only thing can't verify is possibility of magnum primer getting mixed in but with minimum starting charge for powder using, don't see that causing this mess. Have double and triple checked everything postulated initially."

Folks seem to think that because they have not overcharged a case in X number of years reloading, they could not do it this time, and rule that out. This leave them in the dog chasing it's tail mode and some unknown and mysterious cosmic cause of the blow up. They certainly could not have made any mistakes...no not them, they are experiences and these things only happen to newbie bozos.

With a very high degree of certainty, he is wrong. There is a human tendency to deny they are indeed human. The longer folks do things the greater the tendency for the body to go on autopilot while the brain goes somewhere else.

Take these mysterious kabooms with a very large grain of salt.

[TXGunNut]

My best guess is a simple part failure possibly coupled with another failure but it certainly looks like an overpressure event. One problem with the shed jacket theory is that the point of impact of the bullet core would have almost certainly been outside of the previous group. OTOH there's one theory that always works; "sometimes guns just blow up."

[shooter93]

I have helped out at either a gun shop or a Gunsmith's shop forever and have seen a ton of catastrophic failures, some overloads I'm sure and a few SEE.....and every single one of them...."was not the shooter/reloaders fault" It just had to be a bad gun or a bad factory load even though they were shooting reloads that day. I'm with Char-gar. We're all human and I haven't met a one who can't make a mistake.

[BrassMagnet]

A "cracked case neck which is good enough for 'one more load'" could be the culprit in a semi-auto. If the case neck does not have enough tension to hold the bullet through the loading cycle, the bullet can be pushed back into the case with the powder and then any powder charge becomes a catastrophic overload.
The same goes for an un-sized, undersized, or otherwise loose neck.

[Artful]

This is his story;

"My kaboom was with rifle I built with known parts and ammo I loaded. So unless this is a total fluke have no idea. No way any cases got overcharged and pulled down many remaining to verify charge was correct. No sign of obstructed bore, no powder mixup, correct bullets, BCG and gas system had run ~500 rounds flawlessly since built and seemed perfect.

Take these mysterious kabooms with a very large grain of salt.

You left out "using CFE223 which even at starting loads fills case pretty well."
So couldn't be a double charge without powder overflowing the press.
Wrong powder - possible but if he followed the rule to only have one powder out at a time - doubtful. Bullet Jacket in the barrel, my thought is it would leave a bulge in the barrel which should be detectable visually and with the slugging he did.
I doubt putting a magnum primer in would raise pressures up enough to do that.
Defective part - possible but with lab looking it over ...

[leeggen]

Seems the first words are I just don't beleive it was a human error. Cracked case neck, if used is a human error. Wrong powder, human error. Maybe gun was not put together correctly, human error. Squib, I know the bullit hit the target I saw it! ( human error) There is very very few "just accidents". Kabooms are like car accidents--- could not be my fault! I hope no one has a kaboom not a fun thing to be around.
Saw a guy fire 3 squibs before he saw a knot on the side of the barrel of a 22-250, he was experminting with a NEW POWDER.
CD

[Geraldo]

A "cracked case neck which is good enough for 'one more load'" could be the culprit in a semi-auto. If the case neck does not have enough tension to hold the bullet through the loading cycle, the bullet can be pushed back into the case with the powder and then any powder charge becomes a catastrophic overload.
The same goes for an un-sized, undersized, or otherwise loose neck.

This seems the most likely. The damage looks like bolt guns I've seem with overloads or inappropriate powders, but from the shooter's post it seems neither of those was possible.

[frkelly74]

I have picked up new Factory rounds that have the bullet pushed back into the case and these have been usually with other brass that has loose primer pockets and missing primers. I concluded they were factory rounds because the box was present and a sales slip. A semi auto can be hard on ammo and move bullets around during loading. I do not think it takes too much of reducing the volume to really jump the pressure. The possibility of 6mm bullets could really get things going if you could get that to chamber. Anything can happen and eventually it will.

[texassako]

I saw a few things I did not like over there. The bullets were from an estate sale and had 6mm bullets mixed in, and they were frangible pull downs. It even sounds like he was letting his bullet feeders sort them out. I don't know if it is the cause, but I can imagine that a frangible 6mm shoved in a 223 case couldn't be good if you got it in the chamber. I don't think federal would do much for him on the claim of bad bullets since they were pull downs.

[dtknowles]

Was the case from the previous round examined? I found a piece of brass at the range the other day, actually it was a loaded round stuck into the shoulder and neck of a fired round that had separated from the case. If the separated brass that remained in the chamber was only the neck, the next round could possibly have chambered fired leading to high pressure. In the case I found clearly the case jammed and would not fire, the shooter must have cleared the jam but since he left the round where it lay, I suspect he did not inspect it or determine the cause of the jam.

Tim

[rosewood]

Maybe it was a 6mm bullet that chambered because of a loose neck and it pushed the 6mm back into the cartridge while chambering. Had it been cast, it would probably have shot anyway..

[seaboltm]

I was firing my 250 Savage Ruger 77 with factory loads. While loading I noticed a factory void of brass where the case begins to bottleneck. I don't know what would have happened if I had fired that round, but it was missing much more brass than just a mere cracked neck, and right on the area of headspace. I noticed it because the void was facing up as I inserted it into the magazine. What if it had been pointing down? I will never know. The ammunition was factory loaded Remington Core-Lokt.

[Char-Gar]

I was firing my 250 Savage Ruger 77 with factory loads. While loading I noticed a factory void of brass where the case begins to bottleneck. I don't know what would have happened if I had fired that round, but it was missing much more brass than just a mere cracked neck, and right on the area of headspace. I noticed it because the void was facing up as I inserted it into the magazine. What if it had been pointing down? I will never know. The ammunition was factory loaded Remington Core-Lokt.

From time to time one will encounter visibly defective factory ammo. Other times the defect won't be visible. Visibly defective ammo is easy to deal with, as you don't chamber a round that has not been inspected by you before being loaded into the firearm.

What happens when you fire defective factory ammo in your rife? If it is a brass defect , that is when you find out how well your rifle handles and vents hot gas. A good design will provide an escape path for the gas before it damages the rifle. However, that is the reason you always wear shooting glasses as a good rifle design won't protect your eyes.

Consider the low numbered 1903 Springfield rifles and the Krag rifle. Both are brittle, but you never hear of a Krag turning into a grenade, as the action design does not trap the gas as did the early 03s before the Hatcher Hole and other gas vents were used.

About 1961 I was firing a 1919 vintage 03 Springfield with a lot of pre-war Remington Palma Match ammo. After the firing of one shot I noticed white smoke curling up around the bolt. I looked down and the striker/firing pin was at full cock and I knew I had fired a round. I ejected the brass and found a good size hole in the side of the case where the brass had failed. Most of the gas had vented as designed out the hole, but some of it went back through the firing pin hole in the bolt and hand enough force to compress the spring and push the firing pin back to full cock. Yes, I did have on a pair of shooting glasses even that far back. The bullet hit the target but spoiled a nice group I had going. No damage was done to the rifle.

[MtGun44]

Certainly all possibilities need to be examined, but when I have a problem
with ammo, I always assume human error (ME!) as the starting hypothesis and see
if I can disprove it.

People make mistakes. Seems too few willing
to just stand up and say - "I probably made some error".

Again - it is CERTAINLY possible something else happened. Efforts should not
ignore equipment failures, but there seems to be a huge tendency to minimize
the human error possibility and look primarily for a mechanical fault. In this
case, the bolt is still locked in place, so it is either a barrel extention failing at
lower than expected pressures (always possible, but fragments should show
pre-existing cracks if this was the situation) or the pressures were extremely
high. It looks like a case head failing due to too high pressure, then the rest
of the failures due to gas pressure in places it was never supposed to be.

Some possibility of an annealed case head, that could be tested by getting
a hardness test on the case head largest fragment.

Reloading errors can cause extremely high pressures. This seems to be the
situation.

So far, I have only made one serious reloading error, but I do know that I
have to be very vigilant every time I go to the bench, because I am human
and I make mistakes.

Bill

[MtGun44]

Reading farther down the posts and he makes several comments which sound really
like misinformation to me.

First, he states he used a magnesium upper and "has built dozens on magnesium uppers".
As far as I know, the standard material for AR uppers is 7075T6 aluminum, usually forged.
I have never heard of a magnesium upper, and I think this is likely an error, but
probably irrelevant and perhaps there are magnesium uppers that I am not
familiar with.

Second, and more significant is he mentions using "pulled Federal Fusion bullets, which are
frangible" and "possibly a jacket had shed in the barrel". This is erroneous information.
Fusion bullets have the copper alloy jacket electroplated onto the lead alloy core, just like
Gold Dot bullets. In my experience testing Gold Dots, the jacket is absolutely integral to the
lead and even under high impact and huge deformation, not the slightest tendency for the
jacket and lead to separate has been seen. Frangible bullets are made of compressed powederd
metals and have no jacket. I think if these are actually Fusion bullets, they are they MOST
unlikely to have a jacket separation of any of them on the market. I wonder where you might
get pulldown Fusion bullets? Typically pulldown bullets come from military ammo and the
military doesn't use Fusion, they are a softpoint hunting bullet.
If these were actually some sort of milsurp frangible bullet, they could have
started coming apart somehow, not sure what would happen but it seems
like nothing good.
Some of the reported info seems questionable, at this point.

I made the serious judgement error of accepting 1000 rounds of ammo along
with an AR purchase. The ammo was in a heavy plastic back and the seller
said he bought it from a commercial reloader. I was a bit skeptical, but not
skeptical enough! Blew the AR bolt to pieces and seriously damaged the
carrier. Very minor damage to the upper, it was reusable. Barrel, barrel extension
and all else was fine. New BCG and back in business.

Pulling down the "commercial reloader" ammo to see what was wrong and
the cases had not been trimmed. I pulled down 985 of them and weighed
about 2/3 of the charges, until it was clear that they were not problematic.
The issue was severe overlength cases. The worst one I found was 0.025"
longer than the maximum allowable case length and MANY were at least .010
longer than max. Trimmed them all, replaced the powder and bullets and
the ammo was fine.
People make mistakes. And his blowup was a REALLY high pressure event,
mine caused dramatically less damage, essentially blew the bolt to shards,
cracked and deformed the carrier and wrecked a magazine.

Bill