I decided to jump on this bandwagon because I'm weak-willed.
I put together an upper (bought it complete from BCM), added a criterion 1-6.5 22" barrel, torqued it to the upper per instructions, and added the necessary bits (rifle-length gas tube, low profile gas block. Barrel came pre-dimpled for the set screws, which I red loctited in. MI forend, which is neither here nor there. 6.8 bolt in a Colt complete carrier group (other than the bolt).
I can't get it to function with 2 different types of ammo (75gr Fed and 88gr Hornady). The federal ejects most of the time, but won't pick up a new round. The hornady won't even eject. I tried it on a carbine and rifle lower group - both factory duty weapons at my work that have a history of functioning reliably.
I took everything apart, made sure the gas tube was in the right place (centered in the port on the gas block, all of which is directly over the gas port). Gas tube is straight as an arrow in the upper, no dragging. Barrel not showing and carbon from blow-by from the gas block. I watched the bolt cycle - it is just not going back all the way.
I've tried two different lubes (slip EWL and break free). I tried over-lubing and running it less wet. I've tried cleaning the barrel and chamber. Nothing but factory ammo.
Help me obi-wan. Where to I need to look now? PS - I'm full-time firearms instructor/armorer for a smallish police department (100 officers). I take apart AR's pretty much weekly, and have been to several Colt armorer schools over the years - I'm stumped.
I don't know what the gas port size should be on this thing, and frankly I've never measured or messed with port size because we always buy factory guns that tend to run like tops with factory ammo.
Any and all suggestions appreciated.
PS - this is the most accurate .22 caliber centerfire I've every shot with the 75 gr, but shoots like ass with the 88gr stuff. But it's a straight-pull bolt gun, which is not what I was looking for.
I put together an upper (bought it complete from BCM), added a criterion 1-6.5 22" barrel, torqued it to the upper per instructions, and added the necessary bits (rifle-length gas tube, low profile gas block. Barrel came pre-dimpled for the set screws, which I red loctited in. MI forend, which is neither here nor there. 6.8 bolt in a Colt complete carrier group (other than the bolt).
I can't get it to function with 2 different types of ammo (75gr Fed and 88gr Hornady). The federal ejects most of the time, but won't pick up a new round. The hornady won't even eject. I tried it on a carbine and rifle lower group - both factory duty weapons at my work that have a history of functioning reliably.
I took everything apart, made sure the gas tube was in the right place (centered in the port on the gas block, all of which is directly over the gas port). Gas tube is straight as an arrow in the upper, no dragging. Barrel not showing and carbon from blow-by from the gas block. I watched the bolt cycle - it is just not going back all the way.
I've tried two different lubes (slip EWL and break free). I tried over-lubing and running it less wet. I've tried cleaning the barrel and chamber. Nothing but factory ammo.
Help me obi-wan. Where to I need to look now? PS - I'm full-time firearms instructor/armorer for a smallish police department (100 officers). I take apart AR's pretty much weekly, and have been to several Colt armorer schools over the years - I'm stumped.
I don't know what the gas port size should be on this thing, and frankly I've never measured or messed with port size because we always buy factory guns that tend to run like tops with factory ammo.
Any and all suggestions appreciated.
PS - this is the most accurate .22 caliber centerfire I've every shot with the 75 gr, but shoots like ass with the 88gr stuff. But it's a straight-pull bolt gun, which is not what I was looking for.
