HP Bolt with +2" rifle gas system benefits?

[gpr]

I have been fighting with a left hand Stag AR-10 for a while now, as it simply never has performed as well as i would like. I have tried dozens and dozens of different loads with different bullets, powder etc... It seems to never shoot as accurately as i would like. Plus it always is tearing up brass by leaving terrible ejector marks (bad enough some are like burs you can feel with your finger even on factory ammo)

I currently have a 20" barrel with adjustable gas block, rifle length gas tube, JP heavy SCS.

I was thinking about getting a 22" barrel with the +2" rifle length gas system, and a HP bolt. How much benefit will i see from these two changes? Does the +2" gas system really help much? I'm wondering if this would reduce the excessive pressure sites I am getting on the brass by opening the bolt later?

Also does the HP bolt really do anything other than simply have a smaller diameter firing pin? I don't have an issue piercing primers so I'm wondering if i would even benefit by changing out the bolt???

I'm too the point where I'm debating on abandoning that gun and building another as I'm sick of dealing with the limited parts and issues of a left handed stag AR-10, especially with the terrible products and customer service from Stag.

 

[drewthebrave]

If it's not shooting accurately, my first thought is always that there's something wrong the barrel/chamber/bore. The extractor issue could be a side effect of over-gassing, but since you have an adjustable gas block, I'm assuming you've adjusted that to see if it affects performance. Maybe your extractor just has sharp edges. A little filing down of the sharp corners could help your brass.

However, neither the gas system or extractor will affect this rifles accuracy problems. What type of ammo have you been shooting? I'm guessing .308 since you didn't say otherwise?

 

[gpr]

Sorry, this is a 6.5cm. i have shot horandy and federal factory loads. I have also spent way too much time and money trying to reload for it, and really haven't found a decent load. This is also my second barrel.... Maybe I just demand too much from a gun that a gas gun will never deliver.....

the factory barrel was much worse, this is a wilson combat barrel i picked up cheap and it is better and lighter but still aint great.

i have the gas block set so it will just lock back on the last round.

The marks on the brass aren't from the extractor but the ejector. I have polished the extractor, and chamfered the edges on the ejector hole. This is better but still shows way over pressure on everything shot out of it.

 

[LRRPF52]

If you chamfer the ejector channel mouth, that often invites brass to flow into that space. You have to be very careful when doing mods to the bolt face. The best thing is to polish the face with a dowel in a drill with very fine polishing compound, then clean and ream/clean the ejector channel from any burrs or debris.

Have you bedded the barrel?

Are you aware that shooting a large frame gas gun requires some different approaches to the fundamentals?

I have taken Krieger-barreled billet receiver AR-10s that wouldn’t shoot better than 1.4-1.7 MOA with known loads, bedded them and replaced some small parts for reliability, tuned them up with certain torque values across the nut, mount, and rings, and voila, .6 MOA 5rd strings out-of-the-gate.

You need a solid mating between the barrel extension and the upper, and have to man-up on the gun by applying rearward pressure, with a solid rear bag set-up.

I wouldn’t waste another round through it though without it being bedded.

Post some pics of your bolt so we can see if it needs to be replaced, as the ejector channel chamfer might be excessive.

 

[ormandj]

I agree, bed the barrel with SS shim stock of loctite (easier, but more difficult to undo). Also, I can count on two hands the number of people I've seen who've shot a large frame gas rifle well. If all you've shoot for precision before has been bolt guns, some of the technique carries over, but there's a lot of nuance since there's so many moving parts. You really have to remove all the variables from the rifle's operating system, to include any play. A lot of people underestimate barrel whip, for example, and have barrels contacting the inside of the handguard where the gas block is, for example. I've seen people loading on bipods and the handguard flexing enough to contact the gas block even before firing for that matter.

Forgive me if I missed it, but what results are you seeing with match ammunition, and what are you expecting? Also, what do you typically shoot in 5+ shot groups with rifles you're not having issues with?