AR-Kaboom

[bgarman47]

If there was a 300BLK in the mix, I can virtually guarantee a round made it into one of his magazines. Maybe he loaded that round, maybe somebody else did, but I'd bet a full paycheck that's the issue.

It's easy to do if you're not paying close attention: Dump some rounds out on the table or reach into boxes and thumb rounds into magazines while talking to your buddies... Not really looking at each round just loading based on feel... It fits in the magazine, it fits in the chamber, it doesn't fit down the bore... Kaboom. Only takes one errant round.

I wasn't trying to say they were loading magazines when the failure occurred. More likely the magazine was loaded earlier in the session. New box of ammo or not, you have to be extremely careful to avoid cross-pollination when you have 300BLK and 5.56 ammo in the same general area.

I would suggest making it a practice to not have firearms chambered in those calibers with loose (as in not loaded in magazines before arrival) ammunition at the range in one session. Ideally, ammo should be pre-loaded into different styles or colors of magazines to mitigate the issue as much as possible.

 

[johntheplinker]

If there was a 300BLK in the mix, I can virtually guarantee a round made it into one of his magazines. Maybe he loaded that round, maybe somebody else did, but I'd bet a full paycheck that's the issue.

It's easy to do if you're not paying close attention: Dump some rounds out on the table or reach into boxes and thumb rounds into magazines while talking to your buddies... Not really looking at each round just loading based on feel... It fits in the magazine, it fits in the chamber, it doesn't fit down the bore... Kaboom. Only takes one errant round.

I wasn't trying to say they were loading magazines when the failure occurred. More likely the magazine was loaded earlier in the session. New box of ammo or not, you have to be extremely careful to avoid cross-pollination when you have 300BLK and 5.56 ammo in the same general area.

I would suggest making it a practice to not have firearms chambered in those calibers with loose (as in not loaded in magazines before arrival) ammunition at the range in one session. Ideally, ammo should be pre-loaded into different styles or colors of magazines to mitigate the issue as much as possible.

I would bet against it being a 300BO. When that happens it tends to be catastrophic, split upper, demolished bolt and carrier, that sort of damage. Not just blowing out the bolt catch and relatively minor damage.

 

[Cameramonkey]

I would bet against it being a 300BO. When that happens it tends to be catastrophic, split upper, demolished bolt and carrier, that sort of damage. Not just blowing out the bolt catch and relatively minor damage.

AND this isnt his first kaboom.

 

[AndreusMaximus]

I would bet against it being a 300BO. When that happens it tends to be catastrophic, split upper, demolished bolt and carrier, that sort of damage. Not just blowing out the bolt catch and relatively minor damage.

That was my initial thought, too. But then I don't have any actual experience in this area, just pictures I've seen online, so then I got to wondering if those sorts of dramatic explosions might be more common for supersonic rounds, but subsonics operating at much lower pressures might cause a less dramatic kaboom?

I keep coming back to this because it really is the most likely. A company I used to work for received roughly a rifle a week that customers managed to shoot 300BLK through and destroy. It happens.

When those rifles came in, what did they typically look like? Were they all like the dramatic photos I've seen with a completely destroyed upper, or were some of them less catastrophic, like what OP described?

 

[bgarman47]

The OP stated the cam pin was broken, carrier/bolt were stuck (likely damaged), and the magazine catch was blown out of the rifle. That's pretty consistent with what most of the 300BLK in 5.56 rifles I've seen look like. Sometimes you'd see a cracked upper, or a chunk missing, but mostly the bolt & carrier absorbed the damage. Sheared lugs, cracked carriers, bolt split at the waist near the cam pin hole, etc.

Destructive testing is part of any military rifle's selection, so if the M16 turned into a frag grenade when it experienced a barrel obstruction it likely would have been redesigned or not adopted.

Edit to add...

This link shows what most of the rifles looked like in my experience:

300BLK in 5.56

The dramatic explosions are often caused by solid copper projectiles that cannot deform like a softer lead core bullet can. Solid copper supers will lead to a more energetic failure. Jacketed lead, especially subs, won't damage the rifle nearly as much.

I think it's more likely for an inexperienced or inattentive end user to load the incorrect ammunition accidentally multiple times than it is for that end user to experience 4 complete mechanical failures. Especially if the cause of the failure was never identified in the last 3 events.

 

[AndreusMaximus]

The OP stated the cam pin was broken, carrier/bolt were stuck (likely damaged), and the magazine catch was blown out of the rifle. That's pretty consistent with what most of the 300BLK in 5.56 rifles I've seen look like. Sometimes you'd see a cracked upper, or a chunk missing, but mostly the bolt & carrier absorbed the damage. Sheared lugs, cracked carriers, bolt split at the waist near the cam pin hole, etc.

Destructive testing is part of any military rifle's selection, so if the M16 turned into a frag grenade when it experienced a barrel obstruction it likely would have been redesigned or not adopted.

Edit to add...

This link shows what most of the rifles looked like in my experience:

300BLK in 5.56

The dramatic explosions are often caused by solid copper projectiles that cannot deform like a softer lead core bullet can. Solid copper supers will lead to a more energetic failure. Jacketed lead, especially subs, won't damage the rifle nearly as much.

I think it's more likely for an inexperienced or inattentive end user to load the incorrect ammunition accidentally multiple times than it is for that end user to experience 4 complete mechanical failures. Especially if the cause of the failure was never identified in the last 3 events.

Thanks for the link, very informative article. That bullet deformation, though... wow. I've never got to see anything like that before.

 

[W3s]

Is it possible to bring the gun to a professional gunsmith? Maybe they would be able to figure out exactly what failed, and more importantly, why?

 

[Hookeye]

Just because a person is being truthful, that does not mean that what they believe to be the truth is actually what happened.

Dont skip steps in problem solving.

 

[2tonic]

The OP stated the cam pin was broken, carrier/bolt were stuck (likely damaged), and the magazine catch was blown out of the rifle. That's pretty consistent with what most of the 300BLK in 5.56 rifles I've seen look like. Sometimes you'd see a cracked upper, or a chunk missing, but mostly the bolt & carrier absorbed the damage. Sheared lugs, cracked carriers, bolt split at the waist near the cam pin hole, etc.

Destructive testing is part of any military rifle's selection, so if the M16 turned into a frag grenade when it experienced a barrel obstruction it likely would have been redesigned or not adopted.

Edit to add...

This link shows what most of the rifles looked like in my experience:

300BLK in 5.56

The dramatic explosions are often caused by solid copper projectiles that cannot deform like a softer lead core bullet can. Solid copper supers will lead to a more energetic failure. Jacketed lead, especially subs, won't damage the rifle nearly as much.

I think it's more likely for an inexperienced or inattentive end user to load the incorrect ammunition accidentally multiple times than it is for that end user to experience 4 complete mechanical failures. Especially if the cause of the failure was never identified in the last 3 events.

This explanation would seem to best satisfy the "Occam's Razor" test.