But I guess I know considerably more than some.
I had a friend ask me to look at an AR15 in 7.62x39 that is not running right.
I was told you'll get no more than 2 consecutive shots before a failure to extract/eject.
My first experience with the platform was some 40 years ago in Marine Corps. boot camp.
After that, I next held an AR15 around 10 years ago.
About 5 or 6 years ago I built my first, then a second, then a third...
So, when the friend asked me to diagnose them problem I thought there was a good chance I could figure out the issue.
I took the rifle home and inspected it.
Looked o.k. at first glance, so I cycled a mag through by hand.
Every last round fed and ejected as advertised.
Took it to the range.
I only took 4 shots before deciding there was either a gas issue (under-gassed) or it was over buffered.
Back home I looked a little closer and found the gas block looked canted to the left just a degree or so.
I called him up and told him that I thought the gas block was out of alignment, but I wanted permission before I started disassembly.
I removed the hand guard (free-float thank goodness and found not only the gas block out of line, but the gas tube wasn't straight either.
I grabbed hold of the gas tube and it spun in the gas block! WTF?
O.K. pulled the flash hider and then the gas block.
Sure enough, someone had sheared the gas block pin off in the gas tube, but there was still a piece in the gas block, and it was enough to keep the gas block from fully seating.
He was getting no gas at all!
I can't believe he got more than one round shot without having to recharge it.
Punched out the broken pieces and found a spare gas block pin laying in my bin of parts.
Installed same and re-assembled.
I need to wait until tomorrow to head back to the range, but I'm confident I've found the problem.
For the most part, these things are just like an adult erector set.
I had a friend ask me to look at an AR15 in 7.62x39 that is not running right.
I was told you'll get no more than 2 consecutive shots before a failure to extract/eject.
My first experience with the platform was some 40 years ago in Marine Corps. boot camp.
After that, I next held an AR15 around 10 years ago.
About 5 or 6 years ago I built my first, then a second, then a third...
So, when the friend asked me to diagnose them problem I thought there was a good chance I could figure out the issue.
I took the rifle home and inspected it.
Looked o.k. at first glance, so I cycled a mag through by hand.
Every last round fed and ejected as advertised.
Took it to the range.
I only took 4 shots before deciding there was either a gas issue (under-gassed) or it was over buffered.
Back home I looked a little closer and found the gas block looked canted to the left just a degree or so.
I called him up and told him that I thought the gas block was out of alignment, but I wanted permission before I started disassembly.
I removed the hand guard (free-float thank goodness and found not only the gas block out of line, but the gas tube wasn't straight either.
I grabbed hold of the gas tube and it spun in the gas block! WTF?
O.K. pulled the flash hider and then the gas block.
Sure enough, someone had sheared the gas block pin off in the gas tube, but there was still a piece in the gas block, and it was enough to keep the gas block from fully seating.
He was getting no gas at all!
I can't believe he got more than one round shot without having to recharge it.
Punched out the broken pieces and found a spare gas block pin laying in my bin of parts.
Installed same and re-assembled.
I need to wait until tomorrow to head back to the range, but I'm confident I've found the problem.
For the most part, these things are just like an adult erector set.
And an interesting story. I'm also curious what had to be done to break the pin.
