1 1/2 oz of shot may be a tad high. In registered Trap, the max is 1 1/8 oz. An interesting article I read indicates heavier shot charges might not increase your chances of breaking the bird. The basic theory was the at least three pellets must strike the clay to break it, and that means your pattern needs to be fairly closely centered. Outlying strays don't help since you don't have the density to get at least three hits. Two things cause the pellets to scatter out of the pattern. One, the shotcup does not contain all the shot, so the top layers rub against the barrel on their way out. This deforms them, and they quickly leave the pattern. The second reason was that the bottom layers get crushed by the inerita of the layers of shot on top of them, and they also leave the pattern. Using a lighter shot charge reduces these two mechanisms, hence for the shot you do fire, percentage wise more are in the pattern. That extra 3/8 to 1/2 oz of shot just uses more components, driving up your reloading costs, and also give more recoil for the shooter to contend with. For Skeet, I've gone to 1 oz loads and have not seen any lost birds I would attribute to other than my pointing. In Trap, I use 1 1/8 oz because the bird is at 35 yards away when the shot pattern gets up to it.
