Just shoot your CG 20 with 7/8 oz loads. Lots of guys who handload shoot 7/8 and they break clays just fine. Fortunately it seems 7/8 factory loads are more available now than ever. Rio and Cleaver sell them. If you have to have a 12 CG is fine but I prefer Perazzi with fixed M/IM. Preowned is the way to go