Gas port size for rifle length.

[Thevic]

Hi guys thanks for having me on the forum! Forgive me if this topic has been gone over too many times...

For about a year I've been sitting on a Grendel build I have planned and I am finally finding time to port and chamber the barrel...I am using a Bartlein 5R 1/7.75 blank that is profiled for a rifle length gas. Using a Grendel reamer with the same neck as a .264lbc... My plan was to finish it at 20" with an adjustable gas block and I was wondering what gas port size I should use at 20".

I will also be shooting suppressed most of the time so I was starting to hope I can go go down to 18", but can I get reliable function out of a rifle length that short? Someone was telling me to use .102 gas port, but that seems pretty large.

-Vic

[olde sarge]

I think I remember LRRPF52 saying that a rifle length system is designed to function with .094 inch gas port. I measured mine and it is dead nutz .094 with my 20 inch barrel that PF machined for me. Hope this helps but I am sure others with many times more experience than me will have more extensive info as to barrel length and such.

[Drifter]

Link: http://www.65grendel.com/forum/showt...c-18-quot-RLGS

[Thevic]

Thanks guys.

[LRRPF52]

Especially if you are going to suppress it, there is no reason to open up a RLGS port beyond .094" for a 20". For an 18"/RLGS, Hank Rearden got reliable function with .094".

[usmc1371]

My 18 bbl the gas port is .100. I had to try different gas blocks, buffer weights, bolt carriers. I finally got it to cycle.

[LRRPF52]

My 18 bbl the gas port is .100. I had to try different gas blocks, buffer weights, bolt carriers. I finally got it to cycle.

What combo worked for you? Include the load, factory or hand loads as well.

[usmc1371]

I used a low pro gas block. Ar15 bcg. And a h3 buffer. The only ammo I'm using is factory hornady sst. It took awhile for me to get it to work. I ended up putting the gas block right against shoulder. That was the only way I could get enough restriction. An adjustable gas block didn't help much. It just made my hand guard hard to put on. I did notice that my buffer spring was long by about .75. The coils were were fewer and farther apart.

[Thevic]

I think I'll just play it safe with a .094 at 20". I'll be shooting mostly long range anyways so I might as well keep the extra 2"

[usmc1371]

My long range stick the gas port is .09. It is also a 24" bbl. My 18" was built for CQB and shorter ranges.