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AR pistol help

Just adding my .02, though it probably ain't worth that much. From personal experience...We were shooting 3 weeks ago. My buddy had a new Head Down Mk12 Provectus. His was doing the same thing. First shot bang, ejects, loads second round and then nothing with a lightly dimpled primer.

I read where it's been isolated to the lower, and gas problem has been ruled out. I'm just relaying my own experience on a very similar situation.

We swapped Swapped BCG's, same result. Dropped in a heavier buffer, same result. I then noticed his lower receiver was dented above the buffer tube. This shouldn't happen, especially on a new gun with 2 mags thru it. So I assumed it was over gassed as the bcg was slamming into the rear of the receiver. Put my upper (home built) on his lower because I wasn't gonna take the chance of doing the same thing to my receiver. My upper operated perfectly on his lower. He took it to Head Down, they confirmed it was in fact an over gas issue. They were replacing the lower and were fixing the over gas issue. He said adding an adjustable gas block. I would have requested a new barrel. Anyway, haven't fired it since.
 
Just adding my .02, though it probably ain't worth that much. From personal experience...We were shooting 3 weeks ago. My buddy had a new Head Down Mk12 Provectus. His was doing the same thing. First shot bang, ejects, loads second round and then nothing with a lightly dimpled primer.

I read where it's been isolated to the lower, and gas problem has been ruled out. I'm just relaying my own experience on a very similar situation.

We swapped Swapped BCG's, same result. Dropped in a heavier buffer, same result. I then noticed his lower receiver was dented above the buffer tube. This shouldn't happen, especially on a new gun with 2 mags thru it. So I assumed it was over gassed as the bcg was slamming into the rear of the receiver. Put my upper (home built) on his lower because I wasn't gonna take the chance of doing the same thing to my receiver. My upper operated perfectly on his lower. He took it to Head Down, they confirmed it was in fact an over gas issue. They were replacing the lower and were fixing the over gas issue. He said adding an adjustable gas block. I would have requested a new barrel. Anyway, haven't fired it since.

If a lower and upper receiver are machined correctly and within spec, that is not physically possible. The travel distance of the carrier is limited by the length of the receiver extension and the buffer itself. The carrier key should not be able to strike the lower under any circumstances. If the parts are made correctly, the carrier can not physically contact the receivers.

So, I hate to say it, but head down was either covering their own butt or they don't really understand what was happening inside their own gun. Either way, overgassing should never cause physical damage to the upper or lower receiver. Their diagnosis doesn't exactly inspire confidence.
 
If a lower and upper receiver are machined correctly and within spec, that is not physically possible. The travel distance of the carrier is limited by the length of the receiver extension and the buffer itself. The carrier key should not be able to strike the lower under any circumstances. If the parts are made correctly, the carrier can not physically contact the receivers.

So, I hate to say it, but head down was either covering their own butt or they don't really understand what was happening inside their own gun. Either way, overgassing should never cause physical damage to the upper or lower receiver. Their diagnosis doesn't exactly inspire confidence.

In no way do I doubt any of that. I'm I would say a slight tick above average novice. So I'm going to default to your answer. They might have had a bigger issue but felt it was easier to cya and go with over gassed. I can see that happening. Either way, to their credit and which they are none for. They fully warrantied it and made it right. Good company to deal with, local and stand behind their product. There is no doubt though that it was a factory new (less tan 200 rounds) Provectus MK12.

Just so I know for future reference, can you explain a little further? I figured the excessive pressure was causing the bcg to slam rearward with enough force to contact the receiver extension (gas key specifically striking the receiver extension). Again assuming here, but that the buffer/spring retracted fully but excessive force was exerted, enough to strike the the surface of the reciever extension just above the buffer. So I guess my question is, if the bcg moves rearward with more force than the buffer and spring can handle, wouldn't it eventually have to strike the reciever extension?
 
In no way do I doubt any of that. I'm I would say a slight tick above average novice. So I'm going to default to your answer. They might have had a bigger issue but felt it was easier to cya and go with over gassed. I can see that happening. Either way, to their credit and which they are none for. They fully warrantied it and made it right. Good company to deal with, local and stand behind their product. There is no doubt though that it was a factory new (less tan 200 rounds) Provectus MK12.

Just so I know for future reference, can you explain a little further? I figured the excessive pressure was causing the bcg to slam rearward with enough force to contact the receiver extension (gas key specifically striking the receiver extension). Again assuming here, but that the buffer/spring retracted fully but excessive force was exerted, enough to strike the the surface of the reciever extension just above the buffer. So I guess my question is, if the bcg moves rearward with more force than the buffer and spring can handle, wouldn't it eventually have to strike the reciever extension?
Did you or your buddy take any pictures? I'd love to see them.

Does that gun use a collapsible stock or a rifle stock?

The distance that the carrier travels is physically limited. The tail of the carrier itself recesses into the receiver extension, but the buffer behind it will bottom out on the back end of the RE before the gas key can contact the lower. If everything is made to the correct dimensions (lower and receiver extension) AND the RE is installed correctly, there simply is not enough room for the carrier to travel far enough rearward to strike the lower, ever. If it does, something is seriously wrong. This can obviously cause damage to the lower. But it would also likely lead to shearing the gas key bolts and loosening or breakage of the gas key itself. The gun is literally beating itself apart.

The gun would literally have to suffer a catastrophic failure before that could happen. Overgassing will affect the speed of the carrier and can cause malfunctions, but not damage to the gun in that manner.

Sent from my SM-G920V using Tapatalk
 
Did you or your buddy take any pictures? I'd love to see them.

Does that gun use a collapsible stock or a rifle stock?

The distance that the carrier travels is physically limited. The tail of the carrier itself recesses into the receiver extension, but the buffer behind it will bottom out on the back end of the RE before the gas key can contact the lower. If everything is made to the correct dimensions (lower and receiver extension) AND the RE is installed correctly, there simply is not enough room for the carrier to travel far enough rearward to strike the lower, ever. If it does, something is seriously wrong. This can obviously cause damage to the lower. But it would also likely lead to shearing the gas key bolts and loosening or breakage of the gas key itself. The gun is literally beating itself apart.

The gun would literally have to suffer a catastrophic failure before that could happen. Overgassing will affect the speed of the carrier and can cause malfunctions, but not damage to the gun in that manner.

Sent from my SM-G920V using Tapatalk

Ok, that makes sense. So physical dimensions would have the buffer bottom out on the rear of the buffer tube before the back of the key could contact the receiver extension. I guess if I would have simply measured the components that could have told me that I guess. Thanks for clarifying.

Sorry no pics, and collapsible stock fyi.
 
Ok, that makes sense. So physical dimensions would have the buffer bottom out on the rear of the buffer tube before the back of the key could contact the receiver extension. I guess if I would have simply measured the components that could have told me that I guess. Thanks for clarifying.

Sorry no pics, and collapsible stock fyi.
Exactly.

Just looked up a picture of the gun. The reason I asked was if the gun had a rifle stock, rifle receiver extension and the wrong buffer in it, you would have a similar impact. But that's not the case.

Sent from my SM-G920V using Tapatalk
 
Ok, that makes sense. So physical dimensions would have the buffer bottom out on the rear of the buffer tube before the back of the key could contact the receiver extension. I guess if I would have simply measured the components that could have told me that I guess. Thanks for clarifying.

Sorry no pics, and collapsible stock fyi.
Exactly.

Just looked up a picture of the gun. The reason I asked was if the gun had a rifle stock, rifle receiver extension and the wrong buffer in it, you would have a similar impact. But that's not the case.

Sent from my SM-G920V using Tapatalk
Yall have been added to my hero list. Great reading here. Thanks Guy's
 
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