I have a 12 bore Jeffery Invincible boxlock from 1931 with leaf sights for 50 and 100 yards. It has 32" barrels, 3.25" chambers, and according to the records was originally choked 3/4 and full; someone before me opened up the chokes to 1/4 and 1/2, so any rifling that might have been there was removed. I can't make out some words in the record book, but it says "leaf sights for lethal(?) ball, *illegible* bbl".