That is awesome for your boy, my son is also 7 but has not been shooting. I shoot Shockwaves and they load great with an application of a small amount of grease on the sabots. I am looking now for some heavy conicals to try in my 1 in 32" twist gun for use in heavy timber some where in that 525 grain bullet should work. I have heard Powerbelts like less powder charges but they do get the job done. I have wanted to try those Platinum bullets but the prices are so high.