Gas Block Attachment - Set Screw, Clamp, Pinned ?

[Gideon]

Like the subject line states, I'm looking for opinions on gas block attachment methods for a new AR build:

Set screw style - mount, fire, check carbon mark to confirm alignment, drill shallow points where set screw marks are, re-install with Loctite on the set screws.

Same as above but no drilling, just crank down with Loctite.

Same as above but drill and ream for a tapered pin to lock in place.

Use the clamp style, with or without the pin.

Any of the above with green Loctite (intended for sleeves or pins) added under the block.

I'd like to hear your opinions.

 

[smschulz]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

All of the above work.
What is your concern?

 

[Gideon]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

It's my first AR build and I want to make an informed decision on which block to go with and what mounting procedure to plan for.

 

[smschulz]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Honestly, you first have to make sure you have the proper gas to cycle your action.
That means an adjustable for those situations that require variable regulation such as a suppressor or to correct a problem.
The method of attaching really doesn't make that much of a difference, IMO.
I like to use JP Adjustable that clamp on~ on installations that I finish the barrel (keeps from scratching the Cerakote off).
Some use pinned blocks in heavy physical use situations (LE or Mil).
The dimpled barrel bottom installs work fine too and putting a bit of locktite helps keep gas from leaking a bit and theoretically makes it more secure.
I will only use locktite if I know I don't have to take it off again, otherwise you have to heat it up and it is much harder to remove.
All good ~ all work fine, IMO.

 

[BigBlue&Goldie]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

I prefer clamp on for ease of installation. I also read an article by a top gas gun gunsmith (can't remember who) that recommended clamp on as well. Realistically, they have all been proven to work sufficiently.

 

[Hellbender]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

If it's a "bet your life on it" gun that will be shot a lot, solid taper pinned is the most reliable by far, if done properly. Roll pins are not taper pins, BTW.

If it's a target gun wanting the utmost accuracy, esp. if the gas block diameter is .750 or smaller, use a clamp-on type.

I have several guns w/ set-screw types, but they are least desirable in my opinion, I've seen a lot of them loosen up and cause problems. Multiple heat cycles cause the screws to loosen, and aluminum blocks are worse than steel.

I bed them all w/ lock-tite, no reason not to, but if you ever run the gun hard, the gas block will get hot enough to negate the lock-tite, anyway, so don't rely on it for much.

 

[Strykervet]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Well, I prefer taper pins every time. But the Grendel I built has a PRI adj. gas block on it and it has set screws. What I did was install in on the indexing point (there is one dimple just opposite the gas hole already) and once it was straight, I marked the two holes with a marker. Then I bored those out very carefully with a hand drill, not too much, just enough. Then the gas block was installed using Rocksett. This is ceramic based and isn't supposed to have problems with the heat that a firearm can generate. As you imagine, heat won't remove it either. I understand an overnight soak in plain old water will render it useless and it will then come off.

No problems at all so far. That top secret Navy rifle had set screws and so did the new SPR the army took. I think both were changed since to taper pins.

I once tested out an Oly part for my unit. What a piece of junk. <2000 rds. and the gas blew the gas block completely off, along with all three set screws. But as with everything Oly, they don't make mistakes or design changes based on experience, so trash it went.

I hate set screws, but I took a chance on this one rifle and so far have been pretty happy with it. But doing the taper pin is superior every time, and if this one ever comes off it will get modified to pins.

 

[Gideon]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Has anyone actually identified that a set screw block can cause accuracy issues or is that concern just a theory?

 

[country888]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

I like the YHM clamp on, its easy to install & works well. I have never had one to move. Just tighten down good & tight. I don't use loctite, never had any problems.

 

[YetiSlayer]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Taper pin type all the way, more trouble from the start but they just don't fail and once done correctly, then no worries from then on. One less potential reliability issue.

 

[BCP]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Steel + clamping are the best aluminum + set screws are the worst.

 

[Maestro Pistolero]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

For what it's worth:

Jim Fuller at Rifle Dynamics had an AK 5.45 gun come in that had the Bolton Gas Block , which is clamped. The owner had run a suppressor without tuning it for over-pressure. The pressure ripped the gas port in the barrel open to where a hole was exposed ahead of the gas block. The clamped gas block didn't move and the gun still ran 'ported'.

FYI, he'll pin 'em, if you want.

I can also second that the Yankee Hill gas block/FS is GTG. I've run one on a DMR-type build with no problems for about 2k rounds

 

[dixiejarhead]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Steel clamping type. Just say no to differant types of metals. Steel should be on steel. Aluminum ones always have problems eventually.

 

[powdahound76]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Glad to find this. Looking to change my forend and the steel clamp-on wont fit under the FF tube I want to use.
Thanks for the info

 

[ddavis]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

After removing stuck taper pins, I learned that they are to be considered "permanent." They would NEVER come off if you didn't want them to. That being said, I would not put them on my rifle, and I would not buy a rifle with them. They are a pain in the d!ck to change out if you ever need to change your gas block to a low profile, front sight base, or to put a FF tube on. I've had set screw types loosen up, even with a steel gas block. My aluminum clamp on JP has been great since day one. Given the choice, I'd go with clamp on. Less likely to loosen up, and easily removable if need be.
-Dan

 

[stinkyDrunk]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

I have a dimpled set screw setup on a rifle with over 5k rounds on it, including 2500 at a week long carbine class where it was run hard (steel gb). Not a conclusive anecdote, just my opinion that the physical set screw, loctited, will do a better job keeping that gb secured than clamping pressure.

 

[jeff1383]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jerub-Baal</div><div class="ubbcode-body">Has anyone actually identified that a set screw block can cause accuracy issues or is that concern just a theory? </div></div>

I recently switched from a set type screw gas block to a badger ordnance clamp style and saw no difference in accuracy better or worse. Same load same barrel different block same performance.

 

[DavidAR10]

Re: Gas Block Attachment - Set Screw, Clamp, Pinned ?

Split-ring/clamp is the way to go @ 55in/lbs for steel, no loctite required.

Anything that can muck up that design will have you doing a baggage check on yourself.

I run the ARMALITE/JPE 1913 clamp style.