AR 10/15 BCG cycling without gas rings

[Neil Jensen]

I have been shooting HP with a DPMS AR in 308 and 6.5 creedmoor and without gas rings. I modified the bolt so that clearance between the area were the gas rings use to be was made smaller to .001 gap. The action is super smooth and now unlocks more consistently. I have seen the vertical displacement decrease compared to a bolt with gas rings.

I have a Ar 15 bolt done as well and cycles fine. Hoping to find someone who be interested in trying it out and of course returning the BCG when done.

Hopefully to get someone else opinion in how it works. I was thinking BR crowd do a lot of testing with ammo and thought someone would be interested in the idea.

 

[fredhorace77]

Tell us how you performed the work. This is very very interesting, you may have just stumbled upon something great.

 

[Kurz]

I for one have always found the gas rings to be annoying. If you have any more information or a picture or two, I am certainly interested in doing this modification on my own BCGs.

Regards.

 

[Neil Jensen]

I have found by experience that when an AR 15/10 action is not well lubricated or very dirty, the rifle will shoot high shots at 600yds. Often in the 8 ring or higher. When I see new shooters keep shooting high shots I tell them all to lube the BCG and clean it and they will see an improvement.

My own experience with the Ar 10 was that after shooting some 66 rounds for short range, I could feel the binding/sticking of the BCG unlocking. I always seamed to shoot one or two nines at 12 oclock even when I felt I aimed the rifle correctly. The times when I did clean 600yds, it was during a fifty shot NM course of fire. I assumed that the rings were not as dirty and rifle shot better. This happened with either of my 308 or 6.5 creedmoor uppers.

I cleaned my BCG after shooting all the time and re-lube it as well. While cleaning it one afternoon and noticing how sticky it was to pull the BCG to the rear. I wish I could just get rid of the gas rings and just weld it up and machine down to a slip fit back into the carrier. If a M1A piston works, why not with a the bigger AR.

None of my shooting buddies thought it would work to include my gunsmith. But he was willing to do it as he used to be a certified aircraft welder and had access to a stainless steal wire welder. So game on.

I did my 308 first and it still cycled when it was done. I even put an adjustable gas block on the rifle as the BCG cycled very fast now (no drag of the rings anymore) and I slowed it down. First time shooting a 80 shot match I cleaned 600yds and fired a 787 over all. The rifle shot heck of a lot better. I even fired my best 1,000yd score of a 196 with irons and palma match score of 438 as well.

I modified an Ar 15 to see if that worked, and without gas rings the rifle functioned with 55g ball, 69g Fed match, 77g Black Hills match, 77g LC LR, 80g Black hills match. Every time the rifle fire the action locked to the rear. But I can't see the post clearly any more. So shooting this one at distance wasn't much of an option for me.

The upper by itself when held level and then move the muzzle upward a little the BCG unlocks and moves rearward under it's own weight. When nose down slightly it will move fwd and lock up as well. It is that smooth now.

Just looking for someone to help test and report if this idea works or not.

 

[SG4247]

I would be willing to try the AR-10 bolt and see how it compares to the one piece low drag gas ring from JP, installed on a JP bolt of which most of my rifles have installed.

I will either shoot it the 6.5 creed or one of my 6.5x47 guns.

PM to follow

 

[Fast14riot]

I would be willing to try out the AR15 in my service rifle, but I'd really be interested in an AR15 bolt with a .420 bolt face for my prone match rifle.

 

[mac86951]

Interesting, i always saw the gas rings as a tolerance gap filler. Alignment of bolt to BCG and extension is less critical with gas rings to make up the slop; certainly no reason one could make the tolerances tighter; after all 10k rounds is hardly a lot of gas rings wear in all but horribly misaligned uppers. Interesting idea and I'm interested to see how it holds up.

-Mac

 

[Tusker6N]

Is this TIG weld build up and machined to tolerance?

 

[Dusty Stevens]

Whats the downfall of not having them?

 

[Pawnee Bill]

Whats the downfall of not having them?

I would think that galling would be a problem without gas rings. Kinda like running a car engine without rings.

 

[0.1 Aggregate]

Y’all realize that this thread is over five years old and the OP hasn’t been back to the forum in years? Best to check the date before you post.





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[SG4247]

I shot Neil’s bolt and it ran great. Accuracy was slightly improved. BCG was smooth as glass since there is no friction from the gas rings. Did not notice any galling, but the bolt was pretty wet with oil and I only ran a couple hundred rounds.

its a great idea, and I didnt see any negative factors, while I had it in my rifle.