Syrac gas block adjustment on 308

[JDMarshall]

I just got done setting up a syrac block clamp style on my 308 along with a rolling thunder comp. the bbl is 16" with a mid length gas system. While I was at the range today taking it for a test spin I realized I had to run the screw all the way in before I affected bolt lock back, I then backed it out a half turn and spent the rest of the day trying to get on paper at 100.

Running freedom munitions 150gr with no problems since I got this rifle before Christmas.

My iron sight adjustment woes aside, I question the fact that I am running the block with only half a turn of adjustment backed out from bottom. Would this be somewhat normal for a short length gas system on a 308 platform?

I gotta say there was a reduction in recoil but not as much as I was expecting with the new hill comp and syrac gas block, but I guess this is just my introduction to the world of 308 from being used to the soft 223.

[mic2377]

Perhaps the cause of your gas block being barely open is that it is legitimately overgassed. What brand barrel is it? Also any idea what powder they are running in the loads? Some of the slower powders (ie Varget) can make for higher port pressure on autos.

I wouldn't be concerned as long as it runs OK, I don't think it will be as soft as 18" rifle gas system though. I also have to ask, what buffer system are you running? Is it the carbine buffer tube with the goofy little 308 buffer?

Edit: Can't spell

Edited January 21, 2013 by mic2377

[co-exprs]

I agree. If you found a setting wbere it works, then go with it. There isn't a brake which will turn your 308 into a 223. You're dealing with 2.5x the energy and more importantly 2x the reciprocating mass. The Thunder is one of the better 308 brakes and if properly tuned will handle well.

[JDMarshall]

The bbl is a CMMG 18" stainless mid length. Buffer is carbine tube with the stubby buffer. Not sure about what powder freedom is using but they are just factory reloads not any built up match loads.

I agree with run it if it works, I just wasn't sure how risky running the gas block with only a 3/4 turn backed off from bottom. I might bump it back another half turn as I have some concern that carbon buildup could be an issue with the screw at its smallest setting.

[Alphamikefoxtrot]

I have a mid length gas, 18" barrel witht he syrac and a SJC comp. I run the JP lightweight carrier/enhanced bolt/captured buffer spring. I shoot Sierra 110's for all of the hoser stuff and Sierra 175's for the long. The 110's feel like my 223. No recoil to speak of. The 175's punch pretty good but both run with the gas screw almost all the way in as well.