Like several other people said, a pass through does help with the blood trail. I shoot a 7mm rem mag and every shot i have taken has passed through, though they didnt go far enough to have to trail. I was considering going to nosler partitions but i think that would probably be overkill the 7mm already has so much penetration on deer that i dont need a bullet like that. You definetly want a bullet that will expand good inside so that i doesnt just zip through, passthrough is okay as long as it does some damage when its inside.