I'm trying to load up some rounds for my 338/300RUM, after i sized up each piece of virgin brass I loaded 20 rounds. While shooting these loads I noticed that a few of them felt tight in the chamber while some felt normal. What i mean by that is while closing the bolt of a few of the rounds the handle had a little resistance when closing the bolt. and some of the rounds didn't have the resistance. after noticing this I went back home and started chambering some of my unfired brass (that hasn't been loaded) that has only been through the 338 sizing mandrel. some of these unfired and unloaded brass are the same; some have resistance when chambering and some dont. Next, i though maybe i should FL size the brass just to make sure, even though my understanding is that with virgin brass a FL sizing isn't necessary. well after putting one that was hard to close and one that closed easily through the FL size die nothing changed! so what should i do? do i need to worry? I can't imagine that each loaded round will shoot the same if some appear to be slightly longer than others... thanks for your help!