Rock Island does not state what pattern choke tubes the All Generations 20 Gauge Pump Action shotgun uses. I recommend contacting Rock Island for that information. However, there is not a 20 gauge model of the Carlson's Choke Tubes Tactical Cylinder Muzzle Brakes.
Your gun uses the Beretta/Benelli Mobil style choke tubes. Our Coyote choke to fit your gun is item# 30042 and is designed for #4 buck and smaller predator loads.
Yes, we do make this muzzle brake for the RIA X4 Tactical. The Beretta/Benelli Mobil style threads is the correct one.
The Rock Island shotgun uses the Beretta/Benelli Mobil style choke tube. Therefore item# 84030 would be the correct muzzle Brake to fit your gun.
The Mossberg 500 uses the Winchester/Browning Invector style threads. We do make a Muzzle brake for your gun and that system yes.
We do not have info on this model of gun
Yes, item# 84080 will fit the Optima HP threaded barrels.
Your VR80 uses the Ber/Ben Mobil style choke system. Therefore item#84030 would be the one without teeth on the end and item# 84130 would be the version with teeth.