AR is short-stroking.

[smores]

Now is a good time to dimple the barrel so the set screws will have something to hold on to... Or go hard and pin it. If you've already had issues with the block moving you want to be doubly sure it doesn't move again.

I will never install a LPGB without at least one dimple (BCM barrels that come without a FSB/gas block installed come this way), with 2 dimples located using the gas port itself with the BRDE dimpling jig. Pinning is the best way but doesn't work for every gas block.

 

[Kingjamez]

Two things.
First, did you pull the charging handle all the way back and make sure the bolt face was approx. 1/4" behind the bolt stop when it is raised up?
Second, did you try putting drops of oil down through the gas ports on the bolt carrier to get the oil on the gas rings to try and help seal them better?

I can activate the bolt hold open by pushing in the bolt stop an I oiled the gas piston before I shot the gun.

Now is a good time to dimple the barrel so the set screws will have something to hold on to... Or go hard and pin it. If you've already had issues with the block moving you want to be doubly sure it doesn't move again.

I will never install a LPGB without at least one dimple (BCM barrels that come without a FSB/gas block installed come this way), with 2 dimples located using the gas port itself with the BRDE dimpling jig. Pinning is the best way but doesn't work for every gas block.

Yep, there are two dimples in the barrel and hi-temp loctite holding the set screws in place. I think I'd buy a clamp on gas block as the next step if the dimple / set screw doesn't hold.

-Jim

 

[smores]

I can activate the bolt hold open by pushing in the bolt stop an I oiled the gas piston before I shot the gun.



Yep, there are two dimples in the barrel and hi-temp loctite holding the set screws in place. I think I'd buy a clamp on gas block as the next step if the dimple / set screw doesn't hold.

-Jim

Dimpling works better than clamping. And hi-temp Loctite doesn't always work. I installed MANY MANY LPGBs using Rocksett. If Rocksett can keep a suppressor mount attached under all that heat and pressure, it will keep your GB in place.

The ultimate is pinning though. If you want to eliminate your gas block shifting, it's the only way to do it.

 

[jawn]

Dimpling works better than clamping. And hi-temp Loctite doesn't always work. I installed MANY MANY LPGBs using Rocksett. If Rocksett can keep a suppressor mount attached under all that heat and pressure, it will keep your GB in place.

The ultimate is pinning though. If you want to eliminate your gas block shifting, it's the only way to do it.

I've personally had rocksetted things walk on me. I can't believe you actually like Rocksett.

 

[smores]

I've personally had rocksetted things walk on me. I can't believe you actually like Rocksett.

What walked on you? Don't tell me that dude...

It's really only meant for high-temp applications. I have never gauged the temperature of a gas block but I imagine it gets pretty hot. I've never had anyone complain with anything I've secured with Rocksett. Of course everything I secure with Rocksett is torqued properly, the compound is only there to prevent loosening from vibration.

 

[jawn]

What walked on you? Don't tell me that dude...

It's really only meant for high-temp applications. I have never gauged the temperature of a gas block but I imagine it gets pretty hot. I've never had anyone complain with anything I've secured with Rocksett. Of course everything I secure with Rocksett is torqued properly, the compound is only there to prevent loosening from vibration.

I remember when a certain gunsmith was experimenting with Rocksett for pistol sights... and having to re-do a certain Glock 17 RTF2's front sight.

 

[jimbobborg]

Are you sure that the spring is an AR-15 carbine spring and not an AR-10 carbine spring? I've had this happen to me, they look the same, but next to eachother, the AR-10 spring is a little longer and causes this.

 

[smores]

I remember when a certain gunsmith was experimenting with Rocksett for pistol sights... and having to re-do a certain Glock 17 RTF2's front sight.

Yeah I found out it doesn't work for the Glock sights... so I switched back to the factory-recommended "Sur-Lok" stuff and it worked from then on.

I only use Rocksett for suppressor-capable muzzle devices (or for others as specified by the manufacturer) and LPGB screws. Everything else gets Loctite or Sur-Lok (on Glock sights).

 

[smores]

Are you sure that the spring is an AR-15 carbine spring and not an AR-10 carbine spring? I've had this happen to me, they look the same, but next to eachother, the AR-10 spring is a little longer and causes this.

This is a good point as well...

Brownells has an error in their catalog numbers, I remember ordering some Brownells-brand Carbine Action Springs, and they were definitely A2 rifle-length.

I will check my AR-15 notes when I get home and post the correct spring length (uncompressed) so you can check it with a tape measure.

 

[Kingjamez]

I'm fairly sure I've got the right recoil spring, I took it out of a working AR and I don't own an AR-.308

-Jim

 

[Kingjamez]

I took the rifle out today with the correctly aligned gas port, and all was perfect. The gun ate everything including crap wolf. I'm pretty happy with the gun now.

 

[Meditator]

You might also check the recoil spring and try a shorter one. I found this out when buying a RRA pistol lower from another guy who couldn't figure out why this AR wouldn't pick up another round. I happened to have a RRA carbine w/ shorter recoil spring- switched it out and the RRA pistol ran just fine. Good for me, since I only paid $150 for a complete pistol lower.

 

[Sleeping Troll]

Did you figure out exactly what it was? I had a quick readthrough of the thread. Friend is having same issue. He should check his gas block from what I read? He was thinking replacing the buffer tube weight and spring.