carmy53,
you won't have any problem setting the winchester into a rail mount. i have built several naval carriages for the winchester barrel. the mount that you are looking at is for the herreshoff which has .75" trunions. i believe the winchester has .625" trunions. the holder is a perko product and the mount is cast bronze. i made the patterns for it. check with rbg cannons to see what they are getting for it. i don't know the dimension of the barrel at the trunions at this time. we are waiting for the champlain canal to open so that we can get our boat home.
lendi