The old British standard is the 96/1 rule. Or 96 oz of gun to 1 oz of lead. That equates to 7 1/2# for 1 1/4oz shot or 6# for 1 oz. Of course, today's soft recoil pads can up that a bit or an automatic should you be a heathen.

Of course, serious shooters can go higher. A friend and his wife are BOTH in the Trapshooter's Hall of Fame. He uses a Krieghoff which I imagine is 8-8 1/2# and uses 1 oz and 7/8oz for doubles. I imagine the 7/8 oz is for the first shot. Of course for the hundreds of rounds shot in a day, that is a good idea. He has over 600,000 rounds out of that one gun. He sends it in every two years to be rejuvinated.