Big I have the exact same setup as you. Two years ago I put a 209 kit on my lil Wolverine and I shoot 200gn Red Hots (Barnes) in front of 2 50gn pellets of Pyro and I have gotten nothing but 1.5" -1.75" groups from a bench at 100 yds. Are you swabbin your barrel properly between shots? The lil Wolverine should get much better than 4" and you certainly shouldnt accept that (tho thats realistically ok for most hunting ranges youll be shooting that gun, many guys in shotgun only states are shooting those kinds of numbers!) Is your barrel ok? Any burrs or bad rust/pitted spots in it?

Stoke that stove and " Leter eat!"
RA