My one experience was with a Citori .410 skeet gun, one of the first to come to the LA area. It was Cyl/cyl and lousy. Would not keep all the shot on a 48" x48" paper @ 20 yards. Purbaugh jugged it to about the equivalent of .410 modified and it was a much improved skeet killer. My only anoyance was that plastic would build up in the recess and needed to be frequently cleaned. It definitely does work! It's my belief that it's a very effective thing to do to a muzzle loader because they still load like a cylinder barrel, but can then give a tighter pattern, for longer shots.
