Mac grenade

[ctbreitwieser]

My cousin was shooting my Mac yesterday with my 147 subsonic reloads when the gun malfunctioned and failed to feed a new round. He racked it back pulled the trigger, then BOOM!! The gun blew up. I'm not sure how it happened but here's the damage.

 

[strobro32]

 

[ferndog1]

MAYBE...

Reload with little or no powder? The primer will usually launch the bullet part way up the barrel. The primer will make a popping sound often unnoticed by the shooter, who cocks the gun to load another round and BOOM.
In your case a stuck bullet may have kept the fresh round from completely chambering and when the fixed firing pin hit it, it went off. Are there two bullets in the barrel? Hope no one was hurt.

 

[Mayday]

Is your friend ok? Malfs like that are shit ur pants scary. Sorry about ur weapon but I am sure someone can fix it. Mayday.

 

[ChuckB]

Ouch, that makes me want to cry.

 

[GUTTERRATT]

WOW that is one of the worst ones I'VE seen. Was anyone hurt ?

 

[medphys]

Based on the chamber being destroyed I'd bet a double charge or a squib followed by partially chambered round.

Are there two bullets in the barrel?

Sux, but you'll be able to buff out those scratches.

 

[jt.kline]

Well at least the lower doesn't look to bad from the angle your showing us. Was there a round stuck in the barrel?? Did you notice when he pull the bolt to the rear if a casing was ejected??

 

[ctbreitwieser]

Luckily he was ok. Which is very suprising since he's a left handed shooter. There are no bullets in the barrel, and there was no damage to my CAC9, so I don't think it could have been a squib. It's possible it could have been a double charge, but I keep all my empty cases in one loading tray, and then move them to another once I've put powder in them, and I weigh every charge on my RCBS 505 scale. So I'm not real sure how I could have double charged one, but anythings possible. The upper is trashed, but luckily the bolt wasn't damaged. I have a spare barrel, so I may just get a new stripped upper since that's all I need. I'm just not sure what to do with lower. I'm sure it can be bent back into place since its not too bad, but I don't know how to go about it for sure. I'm pretty handy with tools, but it worries me a little when it comes to bending a $5000 piece of sheet metal. I really don't remember if a case fell out or not when recocked it, but I don't think one did. Either way, scary as shit, but I was so happy he didn't get hurt that I didn't even think about getting upset about the gun.

 

[bac0nfat]

Is it even possible to double charge a 9mm?

 

[ctbreitwieser]

Is it even possible to double charge a 9mm?

Well I'm loading 3.4gr of titegroup under Berrys 147gr RN for those loads. So I'd say its possible that 6.4gr could probably fit in there. 3.4gr doesn't take up much space.

 

[medphys]

Is it even possible to double charge a 9mm?

Yep.

 

[MAC MAN]

To me the key word here is RELOADS. I stay far away from them. I know it could happen with kind of ammo.

 

[TonyM]

It definitely looks like a squib followed by a full power round. Glad to hear your friend is unhurt.

 

[ctbreitwieser]

Would it be possible for it to be a squib if there's no bullets lodged in the barrel? And would a double charge (only 6.8gr of titegroup) really have that much pressure to split the whole barrel like that? I'm gonna try to get better pics but its hard because I can't get anything apart. The barrel is split about two inches and it trapped the bolt inside. I was really surprised though that my extractor didn't blow out.

 

[StooperZero]

To me the key word here is RELOADS. I stay far away from them. I know it could happen with kind of ammo.

I guess most of us here are ticking time bombs then, it's a shitty reality but the factory price of 9mm subs is horrible.




Ive had more failures with WWB than my own loads, I only had one bad occurrence like the OP in my Uzi due to my own fault of "experimenting with titegroup"

Wear gloves and glasses, this is an unseemingly dangerous adventure we've taken.








What shape of 147's are you using??

 

[m11stuff@hotmail.com]

I have a MAX-11 mk1 upper in the shop for repair that looks like it had the same catastrophic detonation. Customer was also using his own subsonic reloads and took full responsibility for the damage.

I have seen plenty of ringed barrels from squib rounds. They can occur down any length of the barrel. Sometimes the following round clears both bullets down the barrel.

I had one barrel returned that had 7 rounds stacked up behind each other. Customer did not notice anything until the the out of battery detonation on the last bullet. The bullet could not fully chamber due to the blocking projectile and the case blew out. The outside diameter of the barrel still met spec'.

I have seen some chambers become radially stretched from an out of battery, but only by .005" to .010" on the diameter. The gun will still fire, but the rate of fire is higher and the recoil is sharper. Blow back guns rely on the expanding case to grip the walls of the chamber to keep the breach closed until pressures drops.

Back to the OP's barrel, I do not believe it was a squib round or an out of battery. I have read on other reloading forums about subsonic reloads, that use very little case volume, causing a detonation disproportionate to the load. Basically, the theory is that on a normal load or compressed load, the primer flash ignites only the powder right in front of it. The flash propagates through the powder charge in a controlled burn. With a partially filled case, if the primer hole is at the same level or above the powder in the case, when the primer ignites it flashes across the bed of powder igniting more surface area all at once. This causes a much faster and greater peak pressure. Much more than the steel chamber and barrel can contain.

 

[zipakna]

I have a MAX-11 mk1 upper in the shop for repair that looks like it had the same catastrophic detonation. Customer was also using his own subsonic reloads and took full responsibility for the damage.

I have seen plenty of ringed barrels from squib rounds. They can occur down any length of the barrel. Sometimes the following round clears both bullets down the barrel.

I had one barrel returned that had 7 rounds stacked up behind each other. Customer did not notice anything until the the out of battery detonation on the last bullet. The bullet could not fully chamber due to the blocking projectile and the case blew out. The outside diameter of the barrel still met spec'.

I have seen some chambers become radially stretched from an out of battery, but only by .005" to .010" on the diameter. The gun will still fire, but the rate of fire is higher and the recoil is sharper. Blow back guns rely on the expanding case to grip the walls of the chamber to keep the breach closed until pressures drops.

Back to the OP's barrel, I do not believe it was a squib round or an out of battery. I have read on other reloading forums about subsonic reloads, that use very little case volume, causing a detonation disproportionate to the load. Basically, the theory is that on a normal load or compressed load, the primer flash ignites only the powder right in front of it. The flash propagates through the powder charge in a controlled burn. With a partially filled case, if the primer hole is at the same level or above the powder in the case, when the primer ignites it flashes across the bed of powder igniting more surface area all at once. This causes a much faster and greater peak pressure. Much more than the steel chamber and barrel can contain.

ive been reading something similar. but in regards to reloading 5.7 subsonic using either 55gr or 62gr 5.56 or .224 projectiles in the 5.7 cases.. what is being described is; a secondary detonation with using only 3grains of powder in an 11grain case with the 55gr or 62gr projectile. you will lose the brass as it will split open and it causes the barrel to splinter open in a FN P90. the typical projectile weight for the 5.7 is between 20Gr and 40gr. basically those wer emy thoughts were either a round with no powder, than a round with a double charge. or the secondary detonation that ive been reading about

 

[fq1234]

Ive had more failures with WWB than my own loads, I only had one bad occurrence like the OP in my Uzi due to my own fault of "experimenting with titegroup"

Wear gloves and glasses, this is an unseemingly dangerous adventure we've taken.

Very true, I had a WWB squib go unnoticed in my Max-11SF. The next round gave me quite a suprise. The shell casing shredded and a piece of it was buried in my hand. It could have been a lot worse. I won't buy WWB anymore.

Lage was great BTW. They swapped out the barrel for me and inspected everything to make sure it was good to go.

 

[TonyM]

I still believe that a squib followed by a standard pressure round is the most likely culprit.

The phenomenon being discussed with subsonic rounds pressure spiking is generally only even theoretically possible in cases with a significantly larger volume, and using slow powders. The combination of small case capacity and fast burning powder really only leaves 2 plausible reasons, either a squib followed by a full power round, or a double charge.

Based on the OP's description of the failure prior to the gun taking itself apart, I really think the squib is the most plausible explanation.