Help with Adjustable Gas Block

[explorecaves]

company page says on the product page there is a removable set screw for that GB to aide in alignment with the gas port.

[waveslayer]

There is a divot on the bottom of the barrel that a screw on the bottom of the gas port perfectly lines up. I will have to remove it and take a look and measure everything. So guys I will have to break away from the wife and kids... TBD

[waveslayer]

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Can you measure your gas port diameter before installing the block. I'm kinda curious what port was used.

I just took it off and it measured .095" the gas blocks opening measures .150"

What are your thoughts and mounting it I lined up the set screw with the divot.

[Klem]

OK, what I'm talking about is making sure the gas holes are lined up perfectly to maximize the efficiency of your gas system and minimize the sort of carbon fouling you showed us photo's of.

Take a measurement of the distance from the shoulder on the barrel to the centre of the gas hole like this;


It should be at the .300" mark like in the specs drawings for a Lilja;

http://www.riflebarrels.com/products/pdf_barrel_drawings/ar_profiles/M4_navy.PDF

Then measure inside your gas block to see if it is the same, 0.300" from the end of the block to the center of the gas block hole. If it is then hard up against the shoulder is where it should be, like the divot is encouraging the block to be. BUT, if the distance in the block is slightly shorter, to take into account the thickness of a handguard cap, then it needs to be slightly forward of the shoulder and that divot is doing you a disservice.

Another way of figuring this out is to push the block back on the barrel hard up against the shoulder. Now spin the block 180degrees. Does the gas hole in the barrel line up perfectly with the center of the grub screw hole?

[waveslayer]

So I measured the distance of the gas port, the center and it is .300. From the shoulder of the barrel. I need to do the 360 degree test with the gas block. From the end of the gas block to the end of the gas blocks gas port Is.368"

[Klem]

If I understand you correctly you are fine with the block up against the shoulder of the barrel.

I guess Parallax don't think their block will ever be used with a traditional milspec handguard (it would still work but be right on the edge of lining up).

[waveslayer]

the center of the gas block's hole is .300 from the edge of the gas block. so it should line up perfectly... do you think this barrel, being one of the Liberty ones, the short throat is causing the excessive pressure?

[LRRPF52]

[ATTACH=CONFIG]4603[/ATTACH][ATTACH=CONFIG]4602[/ATTACH]

I just took it off and it measured .095" the gas blocks opening measures .150"

What are your thoughts and mounting it I lined up the set screw with the divot.

.095" is way too large for an 18" MLGS with 5.56 and 6.5 Grendel, and requires use of an adjustable gas block to keep the bolt locked as long as possible. I have a Satern like that, and the gas block is basically turned almost all the way in to limit gas flow, and it still runs like a raped ape.

18" MLGS 6.5 Grendel should be .076", since we have a lot of dwell time with that set-up. I know that .094" works great with RLGS/20"-24" barrels in both Grendel and .223, but it is too much for the 18" MLGS. Good thing you have the adj block.

[waveslayer]

.095" is way too large for an 18" MLGS with 5.56 and 6.5 Grendel, and requires use of an adjustable gas block to keep the bolt locked as long as possible. I have a Satern like that, and the gas block is basically turned almost all the way in to limit gas flow, and it still runs like a raped ape.

18" MLGS 6.5 Grendel should be .076", since we have a lot of dwell time with that set-up. I know that .094" works great with RLGS/20"-24" barrels in both Grendel and .223, but it is too much for the 18" MLGS. Good thing you have the adj block.

I agree! Plus to add to the fun... this is a barrel from the Liberty Group Buy... I have been reading that I should send it in and have it reamed by Precision Firearms... Could the short throat add to my issues?

[Walter]

Mark has my barrel or I would measure the gas hole. I hope it is not .095. What more could go wrong the liberty barrels.