20" Green Mountain AR15 Fluted 416SS 1-8 Testing

[padom]

I grabbed one of these ready to go 20" 416SS 1-8 Fluted 223 Wylde AR15 barrels from Green Mountain when they were running their site wide 30% off sale last month.

GM-M20 20" 223 Wylde 1:8 Twist

I took it out and just put some 55 FMJ BT plinking handloads run on my 1050 through it just to get some rounds down it before starting testing. I put 100rd down it that initial session.

I then brought it back to the shop and gave it a good cleaning with Thoroclean then borescoped it. Bore was sparkling clean and gas port looked great. Nice and round, no blowouts and no signs if it picking up copper.

I then loaded up some precision load tests to see what it could do..


20" Green Mountain 416SS Fluted AR15
1-8 twist
223 Wylde Chamber
1/2-28 muzzle threads
Rifle Length gas

MEGA Ambi NP3 matched receiver set
Rubber City Adjustable Gas BCG
Geissele SD-E
Geissele Super Charging Handle
JP SCS Tuned with spring kit
Magpuls PRS
Area419 ARCA MLOK

100yd from the bench


Best load was right in the known charge weight window with 77's and 8208 @ 23.4gr producing half moa accuracy and sub 5 SD's

I'm going to load up a seating depth test with 23.4gr and see if the group shrinks anymore.


77cc over 8208XBR OCW
1xLC
205M
2.26" COAL




69TMK over Varget OCW
1xLC
205M
1.79" Base to Ogive

Varget was slowww. Produced good accuracy at very low charge but ES and SD went sky high at the upper end of charges which were still very slow for a 20" barrel. Not a combo I'd explore further.

 

[FatBoy]

Dude. Stop. This has been the best kept secret for 8 years. They’re already hard enough to get.

 

[TonyTheTiger]

I've been on the verge of buying one of these for years now.

 

[BCP]

I've had good luck with the ones I bought. Compared to other cheap barrels they have a bit better finish, barrel crown looks better, pretty sure they lap them too.

 

[padom]

I just cleaned it after yesterday shooting and it cleaned up real nice and easy. Bore is sparkling clean and the gas port is still nice and round. No gas port blowout and no signs of the port stripping copper