AR10 (DPMS) gas length?

[itchyTF]

Building one not supressed with 24" barrel in 6.5cm.(what else!). Rifle length or +2 gas system and why?

 

[acloco]

Rifle length is fine. Buy an inexpensive adjustable gas block. Helps in keeping the brass from getting beat up when exiting.

 

[M W R]

I have a couple 10s One is with a 26.5 inch barrel. Does fine with the regular rifle length but now wish I would have + 2. Get a little more mildness.

 

[itchyTF]

What does the +2 accomplish?

 

[mac86951]

Rifle length works at 24"; are you building a light weight rifle? If a few ounces aren't a big deal; for 6.5 CM, I always recommend a +2, and I'll recommend a good toolcraft or JP bolt. LR308 bolts often have sloppy firing pin holes.
+2 on the gas port recommended because it syphons pressure from the barrel at a lower pressure location; meaning less sensitive to gas port hole size, and easier tuning of the gas system.
Gas system has little to do with accuracy and lots to to with how long your brass remains useable; no point in adding case head swipe to a piece of brass already getting tossed into the weeds.
6.5cm loves h4350 which is much slower powder than IMR4895 in a 308 which is what the platform was designed around.

Will it work with standard length? Sure thing, I've got one and shoots great. I'd recommend these changes from my lessons learned. Plus the +2 gas tube is not a big investment; White Oak Armament.

-Mac

 

[M W R]

If there is too much barrel length after the gas port, then too much gas flows into the receiver and it can causes issues with excessive recoil and wear on the rifle.

 

[MGYSGT]

I got a +2 once. Ended up opening the hole. That didn't work so then just pluged the hole and drilled another at rifle length. Works pefect now.

 

[457ciSBC]

Rifle length works at 24"; are you building a light weight rifle? If a few ounces aren't a big deal; for 6.5 CM, I always recommend a +2, and I'll recommend a good toolcraft or JP bolt. LR308 bolts often have sloppy firing pin holes.
+2 on the gas port recommended because it syphons pressure from the barrel at a lower pressure location; meaning less sensitive to gas port hole size, and easier tuning of the gas system.
Gas system has little to do with accuracy and lots to to with how long your brass remains useable; no point in adding case head swipe to a piece of brass already getting tossed into the weeds.
6.5cm loves h4350 which is much slower powder than IMR4895 in a 308 which is what the platform was designed around.

Will it work with standard length? Sure thing, I've got one and shoots great. I'd recommend these changes from my lessons learned. Plus the +2 gas tube is not a big investment; White Oak Armament.

-Mac

I concur, I have a 24” 6.5 and it’s fine with the rifle gas length. However, I have a 22” rifle length 6CM that I wish had +2 gas.

 

[Kurz]

Here is some information regarding the '+2' system:

https://www.recoilweb.com/proofs-camgas-barrel-system-125108.html

https://www.tactical-life.com/gear/proof-research-camgas-barrels/

 

[SPQR70AD]

never saw the sense in having a semi auto just for target use. in AR-10 form with 26" barrel would weigh a ton. they beat up brass finicky gas system bullets might get slightly deformed feeding and slamming into the chamber and are expensive. a bolt action Savage to start with is way cheaper more accurate with a lot less headaches. but others get a kick out of it so to each his own.
I have an AR 308 with 20" barrel that is not to heavy for hunting shoots 3 shot 3/4 to an inch groups but not as accurate as my bolts

 

[itchyTF]

At this point this is more of a project (keep the brain active). It is intended for casual target and hunting (not sure what game). The barrel is going to be a fluted bull .936 GB and .925 muzzle. Heavy but the fluting will help some. It really won't be a carry rifle.

 

[epc308]

I had a 16” AR-15 with carbine gas system. Changed barrels, went to mid length. Built a 20” with rifle length gas tube. With each length increase for the gas system, recoil decreased, cases didn’t fly as far, get beat up so bad, and dropped closer together.