This is a super powerful 45-70 +P (or magnum) loading. It is externally identical to SAAMI spec. 45-70 ammo, but internally it generates FAR more power and pressure. So, our 45-70 ammo will fit/chamber into any 45-70 firearm. This all copper expanding 350 grain TSX-FN long-for-weight bullet will penetrate about as deep as the typical premium 400 grain + lead core partition expanding bullet, yet it gives the benefits of a lighter bullet, which means it recoils less and has flatter trajectories.