Problem with new AR build.

[Xringshooter]

So I got it back out to the range today, and put a few more rounds through it. It seems to be locking open on the last round about 75% of the time, the rest of the time it goes far enough back to eject the casing, but fails to lock open. I didnt have any jams though, though I only shot about a dozen rounds through it before I went back to my other AR. Its not entirely enjoyable to shoot with the shockwave brace and the real short barrel lol. You definitely feel more of a concussive force from the shorter barrel and its quite a bit louder.

I still think it is short stroking and maybe getting a bit better as it gets broke it. I would suggest however, as I think was mentioned earlier, to check that the gas block is actually in the right place. Take it off, look at where the port is and mark that location on the outside of the block with a grease pencil or something else. Then hold it up against the barrel so you can match up the port with the hole in the barrel and then see how it relates with the shoulder on the barrel. The port might just be a little shy of being correctly centered on the hole in the barrel. That could be why you are getting some function but it needs that extra bit of gas to function correctly.

[Emptymag]

Didj'a use the piece of uncooked spaghetti method to line up the gas block hole?
Worked for me.

I build AR15s with rocks for hammers, screwdrivers for punches, and duct tape for everything else, so my advice may not be ideal.

[Jhaydeno]

Didj'a use the piece of uncooked spaghetti method to line up the gas block hole?
Worked for me.

I build AR15s with rocks for hammers, screwdrivers for punches, and duct tape for everything else, so my advice may not be ideal.

It*s easier to drop s spent shell casing in the chamber and blow down the barrel. Wiggle the gas block until you get the best flow, then affix.

[Thrillz]

Do you have any sort of linear comp or even a basic flash can? They make a difference - for the shooter at least.

No, just a standard A2 flash hider. I do wanna get a linear comp at some point, or a flash can, something to push the force out in front. When I first started piecing the build out, I had initially thought about getting a suppressor for it, but I decided save that for a .300 blackout SBR build, and just keep this one as is.

As far as the gas block goes, Im fairly sure I had it lined up correct, the gas block hole is a lot larger than the tiny gas port in the barrel so youd really have to have it off center for it to cover the port. But Ill take it off and double check it just to be sure.

[ArmyVet]

You may find the information you need on the following YouTube channel: https://m.youtube.com/channel/UCaUOYvlDrZh5LWILrVDUM4w

[TooBigToFit]

Didj'a use the piece of uncooked spaghetti method to line up the gas block hole?
Worked for me.

I build AR15s with rocks for hammers, screwdrivers for punches, and duct tape for everything else, so my advice may not be ideal.

I'm probably doing the upside down block and mark technique for my next build.

[DavidH]

This isn’t difficult guys. You can fit a plastic drinking straw on the end of the gas tube & blow through to locate the hole. I’ve been doing it this way for years & years. If you have an adjustable gas block, you want it to be max open.

[Emptymag]

The bis-ghetti method is stupid-simple.

I don't know how blowing in the hole would tell me anything.
Gonna have to look that one up!

[Thrillz]

I havent actually checked the port yet. I took it out another time and put around 40 rounds through it. Half brass and half steel. Steel seems to cause the problem a lot more often than the brass does. I dunno. Ill get around to checking it out eventually, but since its not particularly "fun" to shoot, Im not in a big rush. Especially now that Im shooting at a place with a covered pavilion, it would be a little louder and more concussive than when shooting out in the open air.

[DavidH]

The bis-ghetti method is stupid-simple.

I don't know how blowing in the hole would tell me anything.
Gonna have to look that one up!

Are you serious? It*s pretty simple logic....air flows through, it*s open..ergo lined up. Air DOESN*T flow through....hole is NOT open, thus not lined up. Really....not complicated.

Or..if you rather, I could explain how you take the diameter of the gas hole in both the barrel & gas block, then mic the distance to the edge of the gas block & wall of barrel. Then subtract the diameter from each corresponding gas hole edge distance. This gives the center location of each. From there simply subtract the lesser (barrel gas hole) from the greater (has block hole). That Final number Is the distance the gas block should be set away from from barrel wall. I can tell you it*s going to around .020* typically.... but the math will give an exact center. Sooooo....