When is an Adj. gas block necessary ?

[Baddog0302]

Pondering on getting my AR-10 re barreled with a 26" barrel, the OME is 20" and add a brake. I've a little about Adj. GB's , they seam more necessary ?? for shooters that use suppressors and low pressure loads. I plan to use loads appropriate to the Wt. bullet , equalizing factory loads like Fed. match 308 ammo

 

[jfseaman]

I started with an adjustable gas block on my M1 Garand. This was done to reduce pressure on the op-rod. It worked.

I don't like direct impingement so my MSR is a gas piston, in 6mm/6.5 Grendel (aka 6ar, 6arp, 6 fat rat?, 243LBC). I chose the short stroke Osprey. Again, the point is to not slam the action around.

In my opinion, the buffer should not or just barely contact the end of the buffer tube.

I adjust the gas block to eject every spent case but not through them very far.

It's not necessary but it makes life easier for me. Other ways to accomplish the same thing is varying the load or varying the buffer springs.

Hope this helps.

 

[DataSmith]

Necessary or desirable?

One thing that a number of people are looking for is to adjust/reduce the cycle time. It can be more of an issue with a carbine or mid-length gas tube and can really become an issue with a suppressor.

 

[swehrman]

I think they're necessary on an AR-10. Those rifles are almost always over-gassed.

-- Scott

 

[akajun]

I find most ar s gas porta are large. I believe that it's done by the factory to ensure reliability with all ammo. With barrels I have chambered in .223, I have found that .089 usually cycles most . 223 ammo , but I have had to go up to . 093 on a few occasions. I also chambered a 6.5 creedmoor this weekend with a 24" barrel and with . 083 got bolt cycling but no bho. Reaming to .087 gave bho.
It should be noted that these are standard 12.125" rifle length ports. Next ar10 I do may be with the 2" extended gas system that woa uses to increase dwell time.

 

[hpshooter]

White Oak stocks the rifle length +2" tubes, just picked up two of them for a 6.5 AR build. I am going to avoid the adjustable block if at all possible. Shooting companion had the adjustment screw blow out of his. It wiped the threads out of the block. Don't know the brand but they did stand behind it and replaced it. The block was on a .223 AI.

 

[Pres100]

Odd that it blew out..... I tale mine out occasionally to clean the screw so the channel in the scre doesn't get too clogged up that you can't feel the ball bearing ride in the detent. There is so much carbon that I would think that it would seize before blowing out.

 

[ebb]

Most people that want an adjustable gas block reload and don't want to chase a bunch of beat up brass all over the range. When you cut down the gas pressure the bras doesn't hit the forward assist or go very far and usually can be found in a neat little pile. It is way easier on the gun also. I don't know this to be true but I suspect that it would make the gun easier to shoot cause the bolt isn't being hammered into the buffer.

 

[Baddog0302]

I think they're necessary on an AR-10. Those rifles are almost always over-gassed.

-- Scott

The industry uses a "one size fits all" just the same as they do with a 1-10 twist in their 308 AR barrels. but that's another story.

 

[Juma]

http://www.majorpandemic.com/2013/06/troubleshooting-your-ar-build.html