Had to make up my own 2 1/2", easy peazy though for my Field London Gun in 12 bore.
It shoots well with 2 3/4 drams of 1F GOEX and 1 1/4oz. shot. That's a fairly heavy shot load, but with no chokes, works well on birds.
The barrels clean up easily and I don't reload the shells - lots of empty hulls at the trap range, for the "taking".