Greetings from a new to the board Winchester fan. I currently have several in my safe including 3 101's, a Super X1 Trap with multiple barrels and an early 1200 Skeet grade; all 12 gauge. Here's my question. I recently picked up a supposed 1200 Winchoke barrel w/ rib. I want to try it with a modified choke on Sporting Clays. The range I go to has more than a few birds flying farther and faster than my skeet barrels can handle. When I installed it I noticed the vent rib was shorter on the receiver end, as in the rib didn't seat against the rib on the receiver by about a 1/4 inch, and was lower all the way out to the choke end by maybe an 1/8 th inch or so. Otherwise it matches correctly when placed alongside the original WS-1 barrel. I'm reluctant to shoot it till I figger out why this is. Anybody know about this?