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grendel/lbc gas port?

cjgemm

Sergeant
Full Member
Minuteman
Nov 28, 2006
777
35
York, PA
Having a 18" barrel made with a rifle length gas system. Any one have the perfect gas port size that will let it run supressed/unsupressed reasonably well with out requiring an adjsutable gas block?
 
Re: grendel/lbc gas port?

All that i could find, hope it helps
Barrel Length (in) Barrel Diameter (in) Distance from Muzzle (in) Min Port Size (in) Max Port Size (in)
11.5 .625 3.850 .081 .089
11.5 .750 3.850 .086 .094
14.5 .625 8.375 .063 .078
14.5 .750 8.375 .070 .086
16 .625 8.375 .063 .078
16 .750 8.375 .070 .086
20 .625 6.875 .086 .093
20 .750 6.875 .093 .096
24 .825 N/A .089 .089
 
Re: grendel/lbc gas port?

Just a update. I have my RRA 18" Varmint apart and the port is .085 dia and 8.25 from muz end. It,s a mid length.
 
Re: grendel/lbc gas port?

Just my opinion, but I would not run an 18" barrel with a standard length gas set up as there's too little barrel forward of the gas block in order to make it run with 100% reliability and consistency (i.e. you would need to port it with a big port, meaning too big).

The 18" barrels we do are typically mid length gas systems.
 
Re: grendel/lbc gas port?

I read in one of the AR-15 Mags (Book of the AR-15 #3) that when some LEOs got surplus M-16 they were to long for there gun racks, and they cut them to 18" and they worked great. Mind you these were M-16-A2. I'm sure they work but at what percent, not sure. I have thought of taking one of my 20" RRA Predators and cutting it to 18". We will see!