JP adjustable gas block help.

[Jeepocabra]

I bought and installed a jp adjustable gas block and am having issues getting it to run right.

I can get it to eject spent casings anywhere from 2ft to the side to 3 feet side ways and 3 feet back. But no matter where I put the screw I cannot get it to lock the bolt back. My rifle is a RRA upper/lower with a WOA spr barrel rifle length gas system. Before the gas block change it functioned perfect. I believe the block is correctly aligned, but there is no great way to tell.

As another related matter, anyone know what thread that stupid screw is? I backed mine out too far and it went flying while testing.

 

[LoneWolfUSMC]

Re: JP adjustable gas block help.

Have you called JP?

Id definitely sounds like the rifle is under gassed. I would remove it and double check the aligned. When you reinstall it use locktite as a sealer around the block mounting surface and the gas tube. It will keep the gas going where it needs to, not blowing carbon all over the rifle.

 

[Hellbender]

Re: JP adjustable gas block help.

Pull it off and look at the gas port hole on the barrel, you will be able to see if the hole was aligned by the slight carbon ring around the hole.... sounds like it's not.

While it's off, take it and get a screw.

 

[super jim]

Re: JP adjustable gas block help.

If you "very slightly" enlarge the gas port in the barrel, you will have a wider range of adjustment. With the adjustable gas block, you can turn it down as much as you want.

 

[BCP]

Re: JP adjustable gas block help.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeepocabra</div><div class="ubbcode-body"> Before the gas block change it functioned perfect.</div></div>

Send it back and get a refund then.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
As another related matter, anyone know what thread that stupid screw is? I backed mine out too far and it went flying while testing. </div></div>

Or maybe not...

If it was ejecting back and to the right fully adjusted it was probably OVERgassed which can cause the bolt not to lock back sometimes.

My experience with an adjustable gas block on a 556 was (if the barrel wasn't overgassed to begin with) there was a very fine area of adjustment between under and over. I think they are more at home on 308 AR's.

 

[wnroscoe]

Re: JP adjustable gas block help.

The threads on my JP gas block are 6-32. Home Depot will have SS socket head screws and is what I used in mine. Run the screw all the way in and back it out 1/4 turn. My bolt wouldn't lock back with the screw set two turns out either but did once the screw shot out of the block. 1/4 turn was money.

20" DPMS LR308

 

[super jim]

Re: JP adjustable gas block help.

main thing is follow the instructions with the JP block. But sounds like you may need to start more closed than 2 turns and work you way back out 1/2 turn at a time with only 1 round in the magazine at at time. When the bolt locks open, you are correct.

 

[fr3db3ar]

Re: JP adjustable gas block help.

I started mine out @ 2 turns out like the said. I ended up
@ 3.5 turns out for it to lock back.

 

[TonyAngel]

Re: JP adjustable gas block help.

If your brass is being thrown behind you, that is a sign of being under gassed. The 3:00 to 4:00 position is about perfect for an ejection pattern.

As for it not locking back, what stock, tube, spring and buffer are you running. If you're running a collapseable stock with an 18" barrel with rifle length gas, a heavy buffer or spring could give you trouble. Those rigs run smooth as it is. Personally, I'd dump the adjustable gas block. In this case, it's likely a solution looking for a problem.

When you check to see if the gas block is lined up, just pull it off and look at the port in the barrel and note the carbon build up around it. If the hole is in the center of the carbon buildup, then it was centered. If the hole is intersected by the carbon build up, it was misaligned.