case capacity

Thought ya'll might find this semi interesting. I was gonna use some Win brass in 270 WSM to work up some loads since I didn't want to wear out my Norma brass. so I thought I better do a water weight comparision to see how much difference there was in capacity.
I weighed 20 of each and the results were more than I anticipated.

avg water weight for the Norma was 77.2gr of water
avg water weight for the Winchester was 80gr of water.

also interesting was the spread on the two. the Win brass varied from 78.7 to 80.4, (1.7gr) the Norma varied from 76.9 to 77.9.(1.0gr) doesn't sound like much but it amounts to double the variation from highest to lowest.

Was the Winchester brass trimmed and the flash holes deburred? These things would make a difference in the water volume of a case. The norma stuff supposedly doesn't need these things. Of course thats why the premium price tag on Norma.

Also, the brass should be fire formed to your chamber before a real comparison can be made. The dies at Winchester may be slightly tighter than the norma factory

They all had been fired in my rifle and were weighed with the spent primers in place.

It was as objective a comparrison as I could make it.

When I started reloading my 22 Hornet I had cases from factory ammo I tried from Remington, Winchester and PRVI, and they all had a big variation in their dry weight. I don't think a water weight test is useful when a charge is only 13gr or so. I think Rem were the least variation, then Win and PRVI.

FWIW