can anyone on here tell me what type of choke system i have on my model 20 j c higgens 12ga has sears 583.2002 stamped on the barrel the one on mine has the vent holes on sides with bead sight on top i have one choke on it now has f stamped on flat that is used to remove with wrench i see all these types and i just bought a Lyman Cutts Comp Adjustable Choke Tube which just slide in the holder i thought it was the correct size but it has a dia of 1 1/16 approx over the threads and after i measured mine which looks to be 1 1/8 dia over threads now i have to sell that and try to fine the ones which will fit mine i thought the adj would solve all problems of not having 3 chokes to fool with. i just need the correct name type to look for its amazing the names that are used for these sears guns.