AR-15 BS Thread

Have you confirmed gas block alignment? Have you flow checked the gas system?

 

just start from the beginning. Take off the rail, check the gas block, make sure it’s aligned. I’m sure it’s not pinned to the barrel.

It sounds like it’s an adjustable gas block, if you were adjusting it, you might have turned the key the wrong way, so open the gas all the way open and adjust from there, but since it doesn’t look like you are using a suppressor, from a reliability stand point, I would leave it mostly open anyway. Make sure you have an appropriate buffer/weight like any AR.

 

Yes, I ran the adjusting screw on the gas block nearly all the way out....

 

These are the first rounds in the back yard, Seekins adjustable gas block, I'm running a Raineer BCG, the lower was built using all Aero parts.

 

Gas block is in the dimple on the barrel, haven't the faintest idea how to check gas flow....

 

I haven't taken the upper apart yet, everything looks OK visually, the gas block is in the same place as installed, I wasn't tighting up the gas block adjusting screw set screw every time, if that would stop the cycling....

 

The bolt not opening all the way is one indication.

 

Thanks all for the reply.

The gun is new, these are the first rounds shot, just tying to adjust the gas block before going to the range to zero it in. But not doing anything right now. Need to get serious with it, thought it would run fine, but no.

 

Why did you choose an adjustable gas block?

 

You could take a can of compressed air and put the nozzle into the gas tube (receiver end) and gently blow it, you should be able to hear and possibly feel the air blow out the barrel end or back towards the receiver.

 

it's rare and a long shot but make sure the gas ring on the bolt aren't all aligned and the opening in each ring is on top of each other making a channel for gas to pass through. That creates a situation of under gassing and the bolt may not be traveling far enough back to catch.
also maybe too strong of a buffer spring or too heavy a buffer that is limiting travel? All random guesses if you can rule out your gas block which would seem to be the #1 suspect. Maybe buy a non adjustable one and see if that will fix it. If so then you know your gas block is defective, installed wrong, or not being adjusted properly.

 

Yep. I thought this was common knowledge now.

 

can't watch the vid b/c it's blocked at work. But I think I know what it's gonna say. Guess that was one of those little things I read when I first got into AR's and it just stuck. oh well, learn new things everyday.

 

Need to be able to adjust if running a can.

 

Blow compressed air into the gas tube to confirm it's clear, then mount the block/tube to the receiver loosely enough to slide it around. Repeat canned air treatment while shimmying it around until you find the port, witness mark it, then tighten it down.

 

I had a 450 bushmaster that wouldn’t cycle. I had to drill the gas port on the barrel, cycled like a champ then!

 

Didn’t look like he had a suppressor attachment on the end of that rifle. By going with an adjustable gas block now he has issues that might not even need to exist. Rifles can run just fine suppressed and non suppressed with a fixed gas block if they are set up properly

 

Anyone ever build a psa gen 3 pa-10 lower?

 

Common that DIY AR10s are way over gassed. Anything shorter than rifle length gas system will be guaranteed trouble.

I had a carbine length 308 that ripped rims off cases. Buying another (rifle gas) barrel was cheaper than adjustable gas block.

I would see how it shoots with a regular gas block before dropping $$ on an adjustable. Adjustable GB is also a maintenance nightmare. If you don't keep them cleaned and lubed meticulously, they seize up. Ask how I know.