So its a rainy day. Lets reload. I was sorting .308 brass and separated some Winchester and WW Super (Winchester brand too). Some time in the past (1992) Winchester changed the head inside the .308 for a Palma match to increase case capacity. Supposedly they changed over to this for all brass several years later. NOT! NOT! NOT! The WW Super I have is the old head design and the "Winchester" is the new head design with about 1.5+ grain higher capacity....EXCEPT I just happened to be double checking and found a Winchester case with the old head design. Arrggh! Not good if you are loading near max in the larger case capacity design. Unbelievable. This is all recently fired brass too. Where is the quality control? Bet that would have been a flyer! Makes me wonder if Winchester has outsourced some brass manufacture. Be careful out there.
You're mixing brass from different years and different lots, so yes, they can easily be different. If you want all the same, get the same lot all at once. But, yes, the Win quality has not been that great on the newer brass I have on hand.
You guys are probably right. I have 1000 pieces of LC 10 that I am going to use next for the M1A. The Winchester is going in the fouling load pile. I have 300 pieces of older BHA that is from the Winchester days with the semi-balloon head.