Adjustable Gas Block - Need Recommendations

[Okie_Poke]

For 18” RLGS, you won’t really need adjustable gas. You’re at minimum plug dwell time with more bore volume than a 5.56, so right on the edge of the pressure window needed to run the carrier with sufficient momentum for reliable operation.

Suppressed will give you more back pressure, but still runs ideally with RLGS 18” with a .094” port and a .750” gas block journal.

You likely will have a hard time running lighter cup and core bullet weights reliably, like 90gr TNT and below, unless you shoot them suppressed exclusively.

95gr monoliths run the action nicely though, as they are much longer and harder to swage into the rifling.

I have mainly run the Bootleg carriers suppressed, so everything gets dirty anyway with lots of accumulated suppressor back pressure primarily flowing back through the bore and chamber, then into the action.

18” RLGS is very smooth though. Most 18” Grendels are MLGS with .076” ports. The ideal gas port location for 18” is actually Intermediate Length Gas, between MLGS and RLGS.

Precision Firearms and I think Odin Works offer ILGS 18” barrels with matching gas tubes.

The 18” MLGS guns deliver a bit of extra internal carrier bore pressure, which causes slightly faster cyclic rate. I actually tamed my 17.6” Lilja with a Bootleg carrier several years ago.

When I shoot lighter ammo through it, I have to open up the choke to get it timed right. When I shoot factory 123gr Hornady ammo, I run it more choked for 4:30 ejection.

Adjustable Gas Blocks provide more fine-tuning when they work, while the Bootleg only has 4 positions. The Bootleg is more convenient due to its interface through the ejection port with a flat head. Too easy.

Thanks. Lots to consider. I haven’t ruled out entirely a barrel from Odin or PF with the ILGS. But, I’m currently planning to buy a barrel from x-caliber the next time they run a sale. There’s a pretty good shooter at my local club who recommends them for entry level precision barrels and so I want to give them a try (doesn’t have to be this time, but I’m leaning that way right now). They only offer rifle or mid gas systems. I run 123s almost exclusively, so I figured RLGS would be fine. If PF runs a sale on a criterion barrel though, I may do that instead.