Sig556 Gas Valves

[Bret]

I shot my Sig 556 SBR with its original gas valve (marked E opposite UP designation) and the new gas valve (no letter designation opposite UP designation). Oddly enough, the new gas valve didn't seem to toss the cases shorter distances. With either installed, the cases went about 30 feet, +- 5 feet. That leads me to conclude that it's still over gassed even when using the 0.047" diameter gas hole. The only thing that I can think to do at this point is to weld up the holes and redrill them smaller.

[the_1iviper]

i believe the smallest port on my gas valve is drilled at .035 , i can't remember. this was meant for a suppressor setting but it still runs the gun fine without a can. i would like to go with a smaller gas port for a suppressed setting but don't have access to bits that small.

i believe .047 is the gas port size of the SAN 553 gas valve for the "normal" setting , i think the "adverse" port is .051. if it's a 4 setting valve i think the suppressed gas port is .031 with the 4th position being "off" on a SAN 553 valve.

if you have access to bits that small i would start out somewhere between .031 and .035 and see how it runs. i would like to weld and re drill one of my larger ports to .025~.026 to try out for a suppressed setting. also you can notch the opposite side of the gas valve to catch the detent and make a 4 position valve.