So, AR15 guru's...

[jeep78]

Sorry, I meant the difference from the edge of the stop to the holes... So see if my gas block needs to come off that shelf a bit.

Measure the gasport. Not all holes are to spec

 

[SirBannedAlot]

Measure the gasport. Not all holes are to spec

What size should it be, typically? Carbine length system on a 10.5" barrel. I can go get some new drill bits to check... I need a new set anyway...

 

[cmshoot]

What size should it be, typically? Carbine length system on a 10.5" barrel. I can go get some new drill bits to check... I need a new set anyway...

.071”

 

[cmshoot]

Only for the front hole. The rear hole is always 180 opposite of the gas port.

This. I have a jig that will do just the rear hole, or I can dimple both.

 

[jeep78]

What size should it be, typically? Carbine length system on a 10.5" barrel. I can go get some new drill bits to check... I need a new set anyway...

Do a search. The specs are out there on one of the famous AR sites, do not go by "I always set mine at XX inches" info.

 

[jeep78]

10.5" carbine gas guns gave a lot of problems when first introduced. Yup, gas problems.

 

[cmshoot]

Do a search. The specs are out there on one of the famous AR sites, do not go by "I always set mine at XX inches" info.

Crane calls for the gas port to be .071” on a 10.3”.......that’s what I go by for a 10.5” as well and it’s always worked for me.

 

[SirBannedAlot]

Crane calls for the gas port to be .071” on a 10.3”.......that’s what I go by for a 10.5” as well and it’s always worked for me.

Ok, so that converts to a 5/64 drill bit. That's pretty small, I bet that is the size that I use when I drill out drain bolts and things on the bike, so that I can safety wire them. I will double check on that. I think that with a drop of oil, and a slow hand drill, if I tape off the bit so it can't over penetrate and contact the other side of the bore, I should be able to make sure the gas port is the right size, and unobstructed... Who knows, there could be a metal burr in there partially obstructing things... With a hole that small, it wouldn't take much to throw things off, I imagine?

 

[Dirty J]

I wouldn’t even consider drilling that barrel until you ensure the Anderson parts are in spec...

 

[SirBannedAlot]

So my list of things to check, if the shop didn't find anything...

1) Check gas block spacing for alignment and proper covering of the gas port
2) Inspect gas tube for any dents, bends or obstructions
3) Check gas port with a 5/64 drill bit, bit should insert smoothly, if not, carefully ream it till smooth
4) Inspect the gas block itself for any defects
5) Inspect BCG for where it interfaces with the gas tube.
6) Check torque on key, make sure it is tight and staked properly with no leaks
7) Pull bolt out of carrier, inspect, make sure rings are turned and spaced properly so no overlapping gaps
8) ?