What the big deal with Adjustable Gas blocks?

[Eagle1899]

A good example is my "Recce" style competition rifle. 18" mid weight barrel, rifle length gas system, lightweight carrier, solid delrin carbine buffer, rifle length recoil system with carbine spring and a travel reducer(also of delrin, with a through hole), muzzle brake and a Superlative Arms gas bleed adjustable gas block. I run 77 Tipped Match Kings with a healthy dose of Varget. It ejects cleanly, locks back when empty, runs dirty and has the least amount of recoil of any AR I've set up or shot that is of equal weight.

 

[Eagle1899]

On the flip side... I have a 308 Large Format AR that has a two position gas block. Un-suppressed or suppressed. I changed from a rifle length recoil system to a carbine length recoil system. I had a custom heavy weight stainless steel buffer with tungsten weights made to offset the shorter spring and less mass of the shorter buffer. It now works great and doesn't destroy brass or bolt stops.

 

[ronsatspokane]

Yeah, over gassing is the problem, a variable gas block is the solution. On a direct impingement AR the BCG is forced to cycle by gas peeled off the barrel and routed down the gas tube to the BCG. After the BCG is driven to the rear the cavity is then filled with gas. That's why the lowers get so filthy. And when seriously over gassed, as is the case when suppressed, you end up with a face full of gas. Aside from over gassing being hard on parts and brass and adding filth, the real question is how much gas to you want to eat?

 

[Wolfdog91]

Ok well thanks for all the info eveyone! I've been playing with it more and more and I honestly can say I do see the benefit of it no wrecking my brass as much and it does seem cleaner ! Not sure if it's enough to put one of these on Every build because while doing load testing today ....egghh felt like I was chasing my tail a bit