To make the paintballs a little harder hitting you could store a bunch in the freezer. Getting hit with a frozen paintball would be like getting hit with a rock.
That's a great idea
I am his official paintball tech and the last time I regulated the gun I shot at his little red wagon in the yard. It dented the wagon floor with the balls I used. He gets a pretty good welt when hit by them. I can only imagine how it would punish a 2lb squill.