AR-15s have a recoil? Who knew?
Adj gas manifolds are the result of poor manufacturing processes. Most AR barrels are ported with too large gas ports, one size does not fit all, as operating pressures from too large for design situations result in overly energetic bolt/carrier action, you are problems include extraction under pressure, BCG overspeeed, and feeding problems.
Rifle length ports should be .09-.096, mid length .08-.085, carbine .06-.065.
The design port pressure for a rifle length system is 12k PSI, mid length ports pressure runs around 18k, and carbine at around 26k. All with saami or NATO 223rem /556 ammunition.
Most after market barrels are drilled with rifle sized ports. Hence all the issues.
I put one on my self-built groundhog gun. After developing a good handload and dialing everything in, I locked it down with red locktite. I probably didn’t need the adjustable block, but what the heck.
My father-in-law needs a gas block.