Wanted a DI gun to replace my Sig P716 jam-o-matic. When I saw CDNN clearing out the 12.5 inch Sig barrels used for the P716 I figured what the hell. The Sig parts are mostly DPMS compatible and CDNN had a bunch of them including the bolt. Gas tube length was the only big difference I had to deal with. Parts list;
Aero M5 blem receiver set and 10 inch rail, Tactical Grey Cerakote
Sig 716 12.5 inch barrel, chrome lined, .073 gas port
D. Wilson Carrier and firing pin with a Sig 716 dual ejector bolt.
Cotton Arms Adjustable Gas Block
11 inch gas tube custom made by White Oak Armament.
Vltor RE-10/A5SR: A5 Receiver Extension (had to add 50 cents)
PWS MOD2 Carbine Buffer - H3 5.5 oz
Tubbs Flat Wire Spring
LaRue MBT trigger
DPMS upper parts
Aero LPK
Magpul MOE-K2+ Pistol Grip
PSA branded SB3 adjustable pistol brace
This build comes in just over 1 pound less than the P716 at about 8.5 pounds. Much better balance than the 716 and more rail length to work with. The "brace" being adjustable and using a carbine extension tube is the schit! I was thinking the port would be small but no way, I had to crank the gas block way down and it isn't broke in yet. 25 rounds down the pipe and no malfunction except the two fired at the tightest setting of the gas block, ejected but did not lock back. Worked with Lancer and Magpul mags. The bore has to be dead on concentric with the threads, best looking suppressor alignment I have seen to date with the gauge looking dead nuts center. Hope to get the PA 4x16 on it this weekend and see what it will group as well as check out how it reacts to some heat.
Brass ejects about 3-4 o'clock with no suppressor, no swipe, pretty light primer strike;
With the suppressor they land about 1 o"clock and show a little ejector smear;