With jacleted bullets, seating & crimping in one step can be done w/ good results. With soft plated or lead, separate steps tends to yield better results. It can be done either way though.
"Given adequate penetration, a larger diameter bullet will have an edge in wounding effectiveness. It will damage a blood vessel the smaller projectile barely misses. The larger permanent cavity may lead to faster blood loss. Although such an edge clearly exists, its significance cannot be quantified".