I have a savage model 10 brush camo. I fired 1 box of 50 gr, 1 box of 55 gr, 2 boxes of 45 gr Win factory ammo. All of them grouped .75 to .5 MOA at 200 yards. I neck sized all of the brass with an RCBS neck sizing die set. I grabbed my Hornady head space gage and started measuring. After a few readings I measured some of the new unfired Rem ammo and some new Win brass still in the bag. What a mix of confusing numbers. Results.. Rem new ammo 1.562 Rem fired & neck sizes 1.564 ( kind of expected) Rem oal 1.909 Win new brass 1.560 Win fired & neck sized 1.567 (not expected ) Win oal 1.910 The Win fired brass that I neck sized will chamber with force, it's very tight. The Rem neck sized chambers just fine. Anyone else have a similar problem or seen this much difference in expansion?