The clip or action feed will determine your maximum oal with semi autos, levers, and pumps. It's got to be able to work in the action. Single shots or bolts guns shot singly, you can load em out until they touch the rifling if you want, however; I think the rule of thumb is you need at least the bullet diameter in the case. This is mainly for runout, if you try to seat it to far out it will usually be off center. Accuracy will suffer. (Caution: if you load into the rifling, pressures can increase substantially.)
Bobby (not much more than a newbie)