Does anybody know the correct weight of a 350 Legend buffer for a AR?

[gnostic]

I'm finishing a 20 inch 350 Legend barreled AR upper, with a four chamber muzzle brake and carbine length gas system. The lower has the six position M4 carbine length receiver extension. I'd like to shoot the Lee 200 grain bullet. Also, the barrel has one dimple and the gas block has provisions for two set screws. Do I use one or two?

Your input is appreciated...

[Gtek]

In my experience once one leaves the trail of known builds many variables can be found in the bushes. Orifice size, four stock buffer weights to play with, given barrel length and ammo change puts all in play. If it were me it would go first with an adjustable gas block and an H3 buffer, choked down and clicked open till lock back on empty mag then just a little more. If hunt or paper I run mine as soft as they will run, Tact or SD piece gets gassed harder for reliability. The dimple is usually installed on bottom so when that set screw is tightened first it is supposed to align barrel orifice to port in block, then tighten other one. I always check with bore scope anyway, some perfect, some could be a little better but they are fully open (set screw nose and dimple mating is a variable). The adjustable block gives one some control of volume to chase load changes with a click or turn. Remember this weapon throws up in its mouth, less gas, smoother cycle, cleaner running upper. My 2 cents.

[Moleman-]

Standard buffer and non adjustable gas block. There seems to be more guys having under gassed issues with adjustable gas blocks on 350L barrels and heavy buffers. Even with the blocks wide open after adjusting them through their range. When they change to a non adjustable block and standard buffer the issue disappears. A 16"-20" 350L with carbine length gas port location should have about a .0935"-.096" gas port but they are often larger. For reloading, get a decent taper crimp die. The Lee's taper is very short and wants to put a roll type crimp on the case mouth which can cause headspace issues if overdone and you run the risk of bullet setback if too little with not enough neck tension. I have the 200gr Lee mold and the corners of the meplat can get a bit beat up on their trip through the feedramps but they still shoot very well.

[gnostic]

Gentleman, thank you for your input. I'm searching for cases, dies and a bullet mold without success. So my project is temporarily on hold. I haven't installed the gas block so I'll have the opportunity to measure the gas port.
I was considering gluing the barrel and upper together with 620 Loctite or Rocksett, but maybe I should wait and see how it runs before doing anything drastic...