Lets clarify:Been loading for my new 257, has been very frustrating. I am always very meticulous with respect to documentation and weighing charges, brass prep etc. Had 40 rounds of brass, weighed, trimmed cleaned etc. all within 2 grains. was working up a load and picked up a box of Weatherby 100 grain factory ammo. I should clarify, all Weatherby brass, all pulled factory bullets so as new. 60 rounds total, 40 original and just picked up an additional 20. Cleaned trimmed and loaded with the same load. But......never weighed the latest 20 rounds. I loaded them up with the same load, Fed 215GM primer 71 grains of IMR 7828 COAL 3.195 and they were all over the place! I was inspecting each piece and got a hard bolt open...should have been a sign. Then blew a primer. I stopped, pulled all the bullets, weighed the powder charges, all perfect, double checked the length, all same..... I load for 25-06, 30-06, 35 Whelen, 300Win Mag, 300 RUM, etc, what gives. Then weighed the brass. The new 20 rounds I pulled weighed 20 grains more!!! That just might affect the internal capacity.
Did you reuse the pulled factory bullets ? What bullets were they ?
I take it you pushed the live factory primers out before cleaning and trimming the brass ?
The cartridges you weighed , these were empty cartridges, Yes ,?