Lever actions, pumps and semi-autos require FL resizing. Like senior says, it has to do with the strength of the camming in these actions.
Neck sizing is for bolt actions only. And only brass that was fired out of that rifle. New brass and once fired out of another rifle must be FL resized first.
Sorry sunray, but that's just not entirely true.
If you use your levergun for target or just for fun, try neck sizing. It's easier on the brass. You probably won't be able to see any accuracy difference, but that's just the limitations of the short light rifle you are using.
I routinely neck size 30-30 for my model 94 Winchester, and if I get a case that's a bit tight, the action does have enough camming powder, with a good squeeze on my part. That may not be true for cases that have tougher brass, but certainly, the slope shoulders, and thin case walls of the 30-30, are no big deal.
Like Senior, when big game hunting, I do full length resize every round. Not because the rifle won't do it, but rather because I don't want to have to squeeze home a round, when I need a quick shot.
I should note that the small amount of camming power available to the '94, is on loading only. It has SFA when you want to eject. So pay attention to those maximum loads.
On small base dies. I have one rifle that requires all cases to be run twice through a small base die, or my preferred method, once through the small base die, and once through a file trim die.
That rifle is a 308 BLR. It simply will not close on some rounds that have not been through the die.
All my other leverguns make no such demands.
