sharp, i kinda doubt you're getting 500 fps with a .302 lead ball.....it's possible, but on 400 psi my .311 airgun, which is almost exactly like yours, shoot patched *steel* ball at only around 400 fps. that being said, your's might have a quicker opening ball valve, though mine opens pretty darn fast, and i think yours has a bigger chamber, so that'll increase speed little bit...... but still, i wouldn't guess above 300 fps on 165 psi... though it is i suppose possible. also, a marble weighs nearly the same thing as a little lead ball if not less, and is bigger therefor gets more pounds out of a given pressure per square inch, cause a .56 barrel is around .2 square inches if i remember correctly, and because of that it gets 20 pounds out of 100 psi, where as a for instance .1 square inch barrel only gets 10 pounds out of that. obviously, if the projectiles are the same material, the bigger one will be much harder to move, but in this case the bigger on is glass, and the smaller one lead.
