Gas port recommendations for new build

[Rock8296]

Getting new barrel turned for 308 SFAR build and looking for gas port recommendations.

Barrel will be 1:8 SS 16.5" with .750 gb, ar-15 RLGS, will run 90-95% of the time suppressed with AEM5-30K

Primary ammunition will be a mix of Tap AR 168 or M118LR&clones. 

Reciprocating weight, 11.7 for BCG + 5.3ish buffer with 308 flatwire. Not locked into that weight buffer just thought it was a good middle of the road weight. 

I'd like to make this work without any sort of adjustable gas, I don't have a problem swapping buffers to run unsuppressed.

I'm hoping someone would have some insight or recommendations on this. 

Thanks for your time guys. 

[Rock8296]

To add, as I couldn't figure out how to edit the post. 

Original design intent was to run ar-15 MLGS, after doing research I thought that rifle length may give better performance. Barrel hasn't been made yet so I'm not locked into rifle length gas, if midlength gas would give better performance I'd run that. 

 

[98Z5V]

To reliably cycle a 16" or 16.5" .308 Win gas gun, running rifle gas - you need a gas port diameter of 0.105" to run unsuppressed, supersonic ammo.  That information is directly for the recoil system specs you're mentioning. 

 

The AEM5 can doesn't have alot of blowback, so you'll be pretty close to perfect can on / can off.  If you think it's too harsh with the can, you can pick up a heavy buffer to use when suppressed.  HeavyBuffers.com, great stuff.

[Rsquared]

On 7/31/2024 at 9:02 PM, 98Z5V said:

HeavyBuffers.com, great stuff.

^^^^ These are all I run in all of my suppressed rifles. Can't go wrong with them. And they still run fine with the can off.