I have started having some difficult extraction, as in headspace problems, with my 300. Primary extraction just doesn't seem to quite get the job done on about 1/2 of my reloads. I have been able so far to just use my hand to knock the bolt back and remove the casing. All of my loads are 1-2 grains below listed maximums for the bullet/powder combination and show no primer flattening or ejector marks. Got a headspace gauge from Sinclair and what I have found surprises me. The difference between the average of 10 recently fired cases and 10 fully resized cases is .014. Way beyond the .002 to .004 I was expecting. The brass I am using is Federal brass that came from factory loaded ammo. I still have some of that ammo and measured 10 of them as well. My recently fired brass is .024 longer on average than the unfired brass. Is this common? Is it a problem I should be concerned with or should I just reset my sizing die to bump the shoulder back .002-.004? By the way the gun is a 1995 Winchester Model 70 (with boss) and accuracy is very good.