Around 1970 the profile of the crossbolt was changed from square to round. I had a 20 ga Bresica a couple years ago. Shot it well and could cock both hammers at once, most of the time. Missed the left hammer a couple times on wild birds and decided I'd had enough fun. I really enjoyed it and glad I got it, and not sorry about moving it down the road. Still have a nice Husky hammer gun to shoot targets with.