Set Screw Gas Block on a Precision barrel.

[MitchInOR]

The barrel: 18" Compass Lake SPR. I have been running a clamp on folding sight and it has had almost zero use as I'm running a 2.5-10 power scope.

I almost always shoot with a suppressor and it is way over gassed. The bolt slams back hard and after only a few rounds the interior is filthy with residue.

I have been looking at this gas block. It's $100 dollars less than a Switch Block and has more adjustment possibilities.

The only thing is, is that it attaches with set screws. I think I have read that the type of attachment is detrimental to accuracy.

There is also this one, but the DA7 gets better ratings and is cheaper and is cleaner looking.

So, whats it going to be? Set screw or clamp on?

 

[glock24]

Re: Set Screw Gas Block on a Precision barrel.

I've always considered either one a compromise to durability over the original taper pin method. That said, which one is less of a compromise? I wasn't completely sure until I read about a test Vltor did on one of their clamp-on gas blocks. Long story short, they attached a torque wrench to the gas block to see how much force was necessary to rotate it on the barrel. The results were surprising. The barrel index pin sheared off before the gas block rotated on the barrel.

Read here (2/3s down the page)

However, I also hear lots of guys who are satisfied with the set-screw attachment method. I can't say I'm one of them, but if I decided to go that route, the owner of Mega Arms had some advice for me. He said to make sure the barrel is dimpled so the set-screws can sink into the barrel below the surface. He also recommended the use of Flexbar Rocksett, which is a super high temp thread locking compound. It ensures the set-screws stay tight despite the massive amounts of heat generated at the gas block.

Regarding effects on accuracy, I've never seen any conclusive testing. Common sense however would seem to suggest any process that requires altering the original profile of the barrel could negatively affect accuracy through influencing the quality of the bore. This is a big reason why the best barrel makers profile their barrels <span style="font-style: italic">before</span> rifling them. In other words, cross-drilling for taper pins, or drilling for set-screw dimples would be worse than a clamp-on gas block. IIRC, some High-Power shooters used to buy unfinished front sight bases, and then use Loctite to hold them on the barrel instead of taper pins. This was to avoid the need to cross-drill their precision barrel. That's gotta mean something.

 

[MitchInOR]

Re: Set Screw Gas Block on a Precision barrel.

I can see how with the flip up sight gas block that I currently am running if the gun was dropped the sight could get knocked out of alignment. I would think it would be considerably more difficult with a low profile gas block. If the rifle was for LE or military (which I am not) use I could see the benefit of having the gas block pinned.

Compass Lake sent my barrel with a dimple under the gas port so I should be GTG with a set screw gas block.

 

[GAP-10]

Re: Set Screw Gas Block on a Precision barrel.

This from Precision Reflex might work for you. They also have other gas blocks.

http://www.precisionreflex.com/Detail.aspx?PROD=186780

 

[RufDog]

Re: Set Screw Gas Block on a Precision barrel.

http://www.syracordnance.com

 

[Layton]

Re: Set Screw Gas Block on a Precision barrel.

So is there an inherent accuracy advantage with either assuming each is secured properly?

L

 

[Temp9]

Re: Set Screw Gas Block on a Precision barrel.

I've heard good things about the Syrac.

I think you'll find that many, many people are running set screw gas blocks on precision AR's with excellent results. Myself included. If you're dimpling the bore or whatever the argument is, you've tightened the set screw way too much. 20in-lbs of torque is all that's needed.

I will mention that if this gas block will be on a hard use gun (ie. if you're gonna be knocking it around a lot) AND it won't be covered by the handguard, a clamp or pinned gas block is probably a good idea.