Steel size 6, 6.5, or 7 depending on the alloy. I've seen fairly significant differences in pellet weight between manufacturers and even lot numbers. I've had better results with #6 steel on birds like quail as they tended to be further out and going away but #7 steel worked fine on woodcock, rails, and snipe.
For targets I use #6 in place of 7 1/2 if allowed, #7 for everything else.
