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Recommend an adjustable gas block for a 16" DPMS .308

Rust

Couldn't think of anything clever
Full Member
Minuteman
Apr 18, 2001
348
274
Florida
So I've been playing with all sorts of loads with a shorty AR-10 and things range from not quite cycling the action to pounding the crap out of it. Heavy bullets seem to have a very high pressure at the port so I've stopped using that range of loads. I have an inch pattern L1A1 (FAL) with the eleven position gas block and it works brilliantly and would like more or less the same capability on an AR. Matter of fact it's surprising it isn't a factory option on ARs.

I'd prefer a clamp on block as it would make up for minor dimensional differences (meaning very minor). Not sure if I like the idea of set screw attachment putting pressure point(s) on the barrel.
 
JP enterprises. It’s the only adjustable gas block I use. I like the detent on the adjuster, and cut an acces hole through the hand guard for it.
 
JP makes a great gas block but with handguards getting slimmer and slimmer it's hard to find one that will fit it. At least in my case.
 
AR-10s are fickle creatures. On top of bullet/powder/primer combination, there is a plethora of things that will cause problems in these rifles. I run a JP SCS buffer with an LMOS carier and HP bolt. For a gas block i think the bestbout there is SLR Rifleworks. There sentry 9 has 15 adjustable positions and is low profile. This combined with the aforementioned bolt carrier and buffer spring can give you some of the best tuning options to ensure reliability in you AR-10 rifle. JP also makes weighted bolt carriers for use in suppressed weapons.
 
I use JP and SLR with SLR being the preferred block.
 
I've used SLR adjustable gas blocks on 3 rifles so far and I really like them. I have both the titanium and steel models and they all work very well, just as advertised. I agree with you, I can't believe manufacturers sell AR10's without an adjustable gas block. They all really need one in my experience.
 
I'm going to be trying out a few Odinworks adjustable gas blocks.

They are the cheapest I've found with a front adjuster, about $50 on sale (3/4" size).

The machine work looks nice but they are setscrew style. I'm not too worried about it because I don't torque it too much.

I have used a Syrac Ordinance clamp on block and it works well, front adjust but twice the cost and I'm not sure if that company is still around.
 
By front adjust do you mean the adjustment screw facing down the length of the barrel? Or perpendicular to the handguard? I assumed I would want one with side adjustment to keep from having to take the handguard off to adjust.
 
By front adjust do you mean the adjustment screw facing down the length of the barrel? Or perpendicular to the handguard? I assumed I would want one with side adjustment to keep from having to take the handguard off to adjust.

Front adjusting gas blocks have the set screw facing out towards the muzzle. This allows you to insert your adjustment tool (generally an allen key) from the front of the rifle, under the hand guard.

If the adjustment screw was on the side (or perpendicular to the barrel) you would need to take the handguards off. In my limited experience ive never seen a low profile adjustable gas block where the screw doesnt face front.
 
There are several adjustable gas blocks with the adjusting screw to the rear. I don't know why anyone would buy one intentionally but they exist. They are usually cheap and it's hard to tell which end of a low profile gas block you're looking at if it's not on a barrel. That's how I got fooled.

A side adjusting block would be fine if the handguard wasn't covering it or had a conveniently placed hole.
 
SLR is the best available & is adjustable from the front; Seekins is also good, but is a side adjust unit so unless you get luck, you will want to put a hole in the side of the rail to access, it's also cheaper than the SLR.

MM
 
Had a lot of trouble suppressing a 16 in RR, until adding an adjustable gas block from slr. It works very well, adds a little extra maintenance and complexity (differing gas settings). Never tried any other makes, but the slr is working very well for me. Much better than using heavier springs/buffers. It is also used to cut off 1/3 of gas for normal loads.
 
Thanks for the replies. I'll check out the JP, SLR and Seekins. Price isn't an issue, quality is the only issue. If anyone else has any other suggestions feel free to post.
 
For my G2 I tried out the Superlative arms clamp on. Works fine. I normally use the SLR but wanted to try in out. I added a SpringCo green spring and a JP muzzle break and now that 16" is very smooth to shoot.
 
Front adjusting gas blocks have the set screw facing out towards the muzzle. This allows you to insert your adjustment tool (generally an allen key) from the front of the rifle, under the hand guard.

If the adjustment screw was on the side (or perpendicular to the barrel) you would need to take the handguards off. In my limited experience ive never seen a low profile adjustable gas block where the screw doesnt face front.

Just a comment on your last statement, JP makes a low profile gas block that has the adjustment screw on the side and there is no reason you should have to remove the handguard to adjust the gas flow.
 
Just a comment on your last statement, JP makes a low profile gas block that has the adjustment screw on the side and there is no reason you should have to remove the handguard to adjust the gas flow.

Correct, same for the Seekins, which is what I prefer. Adjusting from the side is much easier than reaching in from the front unless your gas block is very close to the front of the handguard. None of my handguards come off for gas block adjustment, although a couple got a small access hole drilled.
 
Correct, same for the Seekins, which is what I prefer. Adjusting from the side is much easier than reaching in from the front unless your gas block is very close to the front of the handguard. None of my handguards come off for gas block adjustment, although a couple got a small access hole drilled.

I did not know that Seekins made a side adjustable block, thanks for pointing that out!!
 
Correct, same for the Seekins, which is what I prefer. Adjusting from the side is much easier than reaching in from the front unless your gas block is very close to the front of the handguard. None of my handguards come off for gas block adjustment, although a couple got a small access hole drilled.
I thought that seekins was a side retaining screw but the actual adjustment was on the front?
 
I thought that seekins was a side retaining screw but the actual adjustment was on the front?

I think the adjustment screw is on the side and the locking screw is on the front on the block.
 
I think the adjustment screw is on the side and the locking screw is on the front on the block.

Adjustment is on the side.

I have different blocks where some have the locking screw on the front and some on the back; doesn't really matter as I never touch them after installing the gas block. The locking screw gets tightened to make the adjusting screw stiff, and then left alone. They work best with a piece of small lead shot in the hole before tightening them down.