Need to turn a barrel down---how far?

[LMTRocks]

I decided to make my 16" 7.62x39 AR a little lighter. It's got a Troy MRF-R rail, which has been "chopped" down to about 10.5" and the barrel is 7.62x39 with a heavy profile under the gas tube. It is .730 in front of the gas block, .875 behind it. The bore is .311 which leaves a wall thickness of .282in.

I'm wondering if turning down behind the gas block to .750 will have any detriment to the stability of the barrel. It's a hunting rifle---it might only see 200rds a year. The muzzle device is a Smith Vortex in 1/2x36 9mm because the barrel came threaded that way.

Any and all help is appreciated. Thank you much.

[Robb Jensen]

I decided to make my 16" 7.62x39 AR a little lighter. It's got a Troy MRF-R rail, which has been "chopped" down to about 10.5" and the barrel is 7.62x39 with a heavy profile under the gas tube. It is .730 in front of the gas block, .875 behind it. The bore is .311 which leaves a wall thickness of .282in.

I'm wondering if turning down behind the gas block to .750 will have any detriment to the stability of the barrel. It's a hunting rifle---it might only see 200rds a year. The muzzle device is a Smith Vortex in 1/2x36 9mm because the barrel came threaded that way.

Any and all help is appreciated. Thank you much.

If it were me I'd take it to .650" front and back leaving the gas block seat at .750"

[LMTRocks]

GotM4---thank you for your reply. I had thought you might be one of the first :)

Sounds like the recipe for your Lightweight build. Thank you sir.

[Marty916]

This might help you choose a profile:
http://www.ar15barrels.com/profiles.shtml

[lanceriley]

it saves a lot of weight...

[AR15barrels]

I would not go below about 0.700" under the handuards.
That's about the equivalent wall thickness as an A1 barrel in 5.56.
Forward of the FSB, you could go down to 0.650" without any problem.