<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Fullsize dies and neck size dies
Correct me if I'm wrong. I thought when you purchase a new case and fired once. You will need a fullsize die. When you fire again and the case will expand to fit perfectly to the chamber therefore you may not need the fullsize die, just use a neck size die. Does it depend on how much the case/brass stretch? <HR></BLOCKQUOTE>
From what I've read, yes. Eventually cases are supposed to need the shoulder 'bumped' back w/ a full-length die. I have about 3-4 loadings so far on my Hornady .220 Swift brass, and don't see the need yet...
Another reason that full-length dies are some times better than neck-sizing is that in the modern world of mass production CNC machining, some manufacturers still don't always get the chambers right in factory guns. If you have a less than concentric chamber (say, the neck is a little off center, or maybe oval), not a lot, but just enough, it can throw you fits when it comes time to neck-size/partial full-length size that brass. You would be only correcting the size of the neck, but your brass would now be crooked or off-center, just like your chamber. Unless your brass gets indexed to exactly the same point in the chamber, i.e. right-side up so to speak, it's going to be wedging in there and putting adverse forces at work on your brass. In that case, you might be better off to either a) get a new chamber ;p or b) full-length resize so tha your brass gets reset to the proper dimensions every time. Not a perfect fix, but kinda makes the best of a bad situation.
HTH,
Monte