[TexasTon]

Surely it says something about weight somewhere, or may say how many pellets are in that load and figure it that way.

Regardless, I would put the heavy (over 1 1/2) piston in and see if it works for the 3 dram load, and heavy 1 ounce slug load, I would bet it works for the others.

It's just to keep the bolt speed down by not allowing too much gas to the piston, to keep from hurting the gun for long term life.

 

[TexasTon]

I don't think either would fall under the catagory of the heavier piston, though velocity is another factor involved. Some things just aren't "by the written word", I think you need to try the heavy piston on each shell, which it doesn't cycle is the one you need to change pistons on.