Round Fires in Magazine - Pics

Boomer

Boomer

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My pal Pounder had an interesting experience last week when a round in the magazine of his custom Brno 602 fired. He said that when he fired his second shot, there was a muffled secondary boom, and a strong smell of powder. It turns out that the 3rd round some how fired in the magazine box. Fortunately no injury was sustained, and ole Pounder still has all digits and eye sight.

The question as to what caused the round to fire is a mystery. There is a spot weld located at the center rear of the box that was ground off that we considered might be the culprit as it was left just a touch high. But the rounds are staggered in the magazine, so the primers would not be in line with it. The weld is also at the bottom of the box, and Pounder believes the round that fired was directly under the bolt. It is also my opinion that the rounds move ahead when the rifle recoils. This is proven by flattened bullet tips, and bullets that are pushed deeper into cases of powerful rifles when the crimp has been insufficient. Despite this, it is apparent that something, somehow, impacted the primer with enough force to fire the round.

Pounder has carried and shot this rifle without incident for more than 10 years. The ammo was Remington factory stuff, so a high primer is unlikely, and the indent on the primer is peculiar to say the least.

So here are the pics. If anyone thinks they can unravel the mystery, jump in!

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Pounder believes this is the order of the rounds in the magazine (left to right) and the ruptured case was directly under the bolt.

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The indent on the primer is unusual, and the mark appears to be impacted on the case head as well.

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The extractor was bent

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The magazine box is bulged on just one side

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The cross bolts in the fiberglass stock let go.

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The stock failed at the bolt handle recess.
 
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Boomer said:
It is also my opinion that the rounds move ahead when the rifle recoils. This is proven by flattened bullet tips, and bullets that are pushed deeper into cases of powerful rifles when the crimp has been insufficient.
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this is true, but only on the initial rearward movement of the rifle, as the rifle moves rearward, it can throw the cartridges back against the back of the mag box as the rifle itself slows down against your shoulder.

from the pic of the primer and your description, it looks like a 1:1,000,000 occurance that a piece of trash (pebble, bit of bedding material) got stuck to the primer

Pretty interesting though, and lucky no-one was hurt. Rifle looks all repairable too.
 
Would it be possible that dirt or or some small piece of metal debris might have been in the mag well or on the end of the case to cause it to detonate with recoil??

Your buddy sure has a horseshoe up his butt to come out of that unscathed.

Really glad he is okay and all parts of him are intact.

Scarey stuff.What kind of damage was done to the seat of his pants ??
 
Your buddy is some lucky.... The heat mangled his 2nd and 3rd rounds and actually started melting the point on round 2 was there powder in the mag or did it ignite as well? gonna guess the whole thing got some hot....
 
Here is a wild-ass guess ...................

I don't think that cartridge "fired" in the magazine. If it had the primer would have been blown out of the primer pocket during ignition.

Without looking at the rifle I would suspect that something let go during the firing of the chambered round and gas and flame drove into the mag box rupturing the first cartridge and deforming the others.
 
Pounder is going to send the rifle out to have it accessed.

The extractor was bent by gas venting between the bolt body and it from the magazine box. Comparing the action to his .416, we noticed more light was visible between the bolt rail and the bolt body of the .458, so it looks as though the action rail bulged.. The floor plate will have to be replaced. It could be that a new CZ 550 would be cheaper than the repair, but it's too soon to speculate.

Whenever I have fired my 602, or one of the others around here, The rounds in the magazine are always tight to the front of the box after the first round is fired. I would think that the pressure exerted on the rounds from the follower would prevent additional movement, and in addition, a lead tipped bullet would not be inclined to bounce once it impacted the front of the magazine box.

While we have not discounted a small piece of debris causing the problem, it is inconceivable to me that with the situated rounds as far forward as possible in the magazine, that any foreign material would drop under the follower. At this time however, that does seem like the most likely scenario.
 
'Boo said:
Here is a wild-ass guess ...................

I don't think that cartridge "fired" in the magazine. If it had the primer would have been blown out of the primer pocket during ignition.

Without looking at the rifle I would suspect that something let go during the firing of the chambered round and gas and flame drove into the mag box rupturing the first cartridge and deforming the others.
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A cartridge firing in a large space will not act like one that is in a chamber. The pressure would act equally on all surfaces, and because the flash hole is the smallest surface, there would be the least amount of pressure on it. So the bullet is against the front of the magazine box, pressure builds, the case is pushed rearwards as the bullet and case separate, and before it can seperate, the case fails in an impressive fashion. It could be that the marks on the primer and case head were caused during the incident rather than causing the incident.

Something I have questioned for a while now is if the anvil inside a primer could break loose from the violence of rounds being fired over it. Aside from recoil effects, there must be some intense vibration on the rounds in the magazine. So, I wonder if an anvil could break loose and vibration cause it to ignite the priming compound?
 
'Boo said:
What I would like to see is a picture of the case that was in the chamber at the time everything went sideways.
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The round that was in the chamber is fine, and fired normally. There is no apparent damage to the barrel, chamber or bolt face. He could probably put the .458 barrelled action in his .416 stock and use it, but it's better to have it checked, and like I said earlier it appears that a bolt rail has bulged.

If you are right about the gas pressure being enough to push out the primer, it supports my theory that the impact mark on the primer was made during the event, when the case pushed rearwards as the bullet moved forward, it would of pushed the primer back into place and a piece of brass thrown behind the case could of caused the mark on the primer and case head.

When I had my house fire several years ago, there were several thousands loaded rounds that cooked off, and to the best of my recollection, none of the ones I examined afterwards had the primers pushed out. This means that when the cartridge is not contained, the pressure necessary to rupture the case is less than the pressure necessary to push out the primer. The gas pressure has much more surface area to work on the cartridge walls than on the flash hole. When a cartridge is normally fired in a chamber, it could be the pressure of the priming mix igniting that pushes the primer out, rather than the pressure of the burning powder charge above it. Then when the pressure is high enough to start the bullet moving, the case is slammed back against the bolt face, pushing the primer back in.

As another example, when I am blasting, the column of explosive in a bore hole fractures and moves rock outwards from the face of the blast, yet there is little damage to the rock at the bottom of the bore hole, and the greatest amount of fragmentation happens in the middle of the bore hole. The top of the bore hole is stemmed with inert material to prevent gasses from venting out before the burden has fractured and moved, and results in some oversize from the cap rock. This is almost exactly what occurred to Pounders cartridge. It failed in the middle, the bullet (stemming) contained the gas until the pressure exce3eded the strength of the wall of the bore hole causing it to fail at the weakest point - in the middle of the case. The least amount of damage was to the head of the cartridge which is the strongest part - like the toe of a quarry shot.
 
Rem. primers

I guess I will jump in here, I have carried this rifle almost every day for at least 6 months a year for about the last 10 years. when I practice every other day, I shoot 5 rounds at a time ( 1 mag. full ) i shoot at random targets at bear range 5yrd. - 25 yrds. The round that let go was the 3rd. rnd. in the mag. The only thing that I noticed that was different was the sound and the smell of burnt powder. When I tried to open the bolt it would not open I noticed a piece of brass about 1 inch long sticking up between the extracter and the bolt body we can't find that piece,when I opened the floor plate the rnds. in the mag. fell out as you see them in Boomers pics as well as some unburnt powder. The 2 rnds. that were fired before them when off as they should have( and on target ). After clearing the rifle I just hung it on the rack and sat for a while. The good thing about this other that I am still in one piece is my wife says I NEED to buy a new rifle.

take care
pounder
 
Mag. Det.

Probably caused by those itty bitty .458 rounds rattling around in that big CZ mag box. Have it checked out, reassemble and punched out to 460 WBY.:)Just made a trade and got my CZ Rigby back. Very happy camper here.:)
 
pounder said:
I guess I will jump in here, I have carried this rifle almost every day for at least 6 months a year for about the last 10 years. when I practice every other day, I shoot 5 rounds at a time ( 1 mag. full ) i shoot at random targets at bear range 5yrd. - 25 yrds. The round that let go was the 3rd. rnd. in the mag. The only thing that I noticed that was different was the sound and the smell of burnt powder. When I tried to open the bolt it would not open I noticed a piece of brass about 1 inch long sticking up between the extracter and the bolt body we can't find that piece,when I opened the floor plate the rnds. in the mag. fell out as you see them in Boomers pics as well as some unburnt powder. The 2 rnds. that were fired before them when off as they should have( and on target ). After clearing the rifle I just hung it on the rack and sat for a while. The good thing about this other that I am still in one piece is my wife says I NEED to buy a new rifle.

take care
pounder
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Just a note to check out the primer, see if you can (safely) remove it and load it into another case like a 308 or 06. Don't load any powder with the round, but use it as a snap cap to check if the primer ignited in the 458. That would at least give some indication of what did and didn't happen....glad you're still here.:eek:
 
This by 303 carbine---

Just a note to check out the primer, see if you can (safely) remove it and load it into another case like a 308 or 06. Don't load any powder with the round, but use it as a snap cap to check if the primer ignited in the 458. That would at least give some indication of what did and didn't happen....glad you're still here.
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This is an excellent idea, only the testing of the primer should be done in a lab, preferably by Remington Peters. In any case, I think R-P should be made aware of the incident and I think they certainly would be interested in seeing the ruptered case.
 
Very scary stuff right there. I'm glad the hear your friends ok. I never saw what flavor of primer was being used. If it was a handload, could it have been a Federal primer? Federals come in a larger box for a reason. I guess they are very sensitive, and they had an incident once. Now they are spaced farther apart than other mfr primers for shipping. Not much help, I know. But a possibility at least.
 
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