Shot shells is an entirely different beast. 12 and 20 is not as cost effective as it once was. I shoot 16 a good bit and savings is substantial there. If getting started I’d recommend a MEC single stage press. Find one published recipe and stick with it. You can’t safely substitute components with shot shells like with metallic loads. Just changing primers can elevate pressure above safe levels. I use the same hull, wad, primer, powder charge, and shot payload for everything. You can change shot SIZE to suit the need. 1 oz of 6 shot loads the same as 1 oz of 8 shot.
I’ll add although you may not realize any savings on 12 and 20 you’ll load a better shell for about the same price as factory. My shot to the grill percentage goes way up with my reloads on a dove shoot so maybe I do save some $ when shooting the 20ga.
