Winchester brass in .308 is significantly bigger than military 7.62 NATO brass. The weight difference I've measured is as much as 33 grains as little as 19 grains. Winchester weight control isn't very tight, spanning about 6 grains in that chambering. In .30-06 the weight difference is much less. I've seen as little as 4 grains difference from LC to as much as 12 grains difference, depending what lot it was. In .223, the difference from other brands is quite small, being within a couple of grains in many instances, which is about like the difference you see in 0.10—0.15 grains of powder. Negligible.
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