308 gas tube length differences ????

[kattman]

Guys

I am putting together some 308 Ar's using the new MEGA ARMS MKM platform. I have purchased two barrels so far, one 18" from Fulton Armory, and one 20" from JP Rifles. They are both listed to take a rifle length gas system tube. If I set the barrels side by side with the extensions even, it appears that the gas port hole on the Fulton is roughly 1/4" inch out farther from the extension then the JP is. JP states that their barrel takes a standard rifle length AR-15 gas tube. Calls and e-mails to FA re this have gone unanswered. If anyone has input on this tube length difference situation, I would greatly appreciate it. Also, I have 18" and 20" MEGA specific AR 308 barrels on the way so I can compare when they arrive.

Thanks for any/all.

Kattman from Michigan

[Todd.K]

The Armalite AR-10 gas tubes are 1/4" longer than AR-15. They also have a taller dog-leg because on a 7.62 AR the center of the bore to the center of the carrier key hole is greater than on an AR-15.

DPMS used AR-15 gas tubes last I checked, so it could be either.

[chococat]

I have a Fulton Armory rifle-length gas barrel. The Armalite AR-10 rifle gas tube is the correct tube for this setup.

That being said, I did mistakenly, start with a AR-15 rifle gas tube (1/4" shorter) and did not experience any malfunctions.

Al

[mic2377]

+2 on the AR-10 tubes being 1/4" longer. I do believe that they are also the correct tube for the Fulton Armory barrels.

However, I also installed a standard AR-15 rifle tube on my 308. It does seem short, but I have experienced zero issues and it seems to make no functional difference.

[mic2377]

Forgot to add that my 308 barrel is a Fulton Armory 20"...

[kattman]

Guys

Thanks for all, have some AR-10 rifle length gas tubes on order. Pretty quiet over at FA??

Kattman from Michigan