I meant to say dimentionally identical. Yes I am well aware that the bronze (GMX) will be much lighter than a wheel weight bullet(cast) . If they all leave the muzzle at (randomly picked)1900fps then they ought to fly the same. They will have the same bc and same flight time as such the mathmaticaly same drop. I'm only concerned with the external balistics not the internal. I'm also aware of the friction issues charge weights,powder choices etc. What about what happens in the last inch of the bbl and the 1st 50yrds out of the bbl that makes shooting a full spire/spitzer/flat based GMX/TSX shaped so flakey that moulds are generally not available and discouraged by all but pro-shooters. Why do they work in the monster500grn 1000yrd 45s but not in the dinky 180grn 200yrd 308 proficiency gun?