Well, did the experiment last night at the range. Fireformed some old used 300 WM brass, annealed 3 and fireformed them, fired the necked up cases and fired a new brass 7 times.
These are what we are working with, from the top, Horn 375 Imposter brass,expanded and fireformed W-W 300 WM to 375 Imposter, new W-W 300 WM brass
These three photos show the line up of the experiment and results, new W-W 300 WM, annealed and fireformed from 30 cal, fireformed from 30 cal unannealed, expanded and fired with 375 bullet, 375 Horn brass for comparison, sectioned new W-W brass after seven full power loads, sectioned old case with unknown firings in 300 WM and it appeared to show incipient separation however section photo tells different.
Close up of how the case blows out at the belt area.
These 3 photos show the sectioned new case which was expanded and then fired 6 times with a 235 gn Speer bullet over 80 gns, RL 15, CCI 250 primer. We just deformed the case mouth a little and pushed the bullets into the case by hand a little bit then seated them with the rifle, using the lands to seat the bullet, then fired. The final firing was a pulled load with 260 NP and Win 760. This load was warm in the W-W brass but no issues opening the bolt, very slight ejector mark and nicely flattened primer. The load 1 gn less in the Horn brass almost seized the bolt on the Ruger and this load was not fired at all in the Horn brass. Primer still good and tight when I pushed it out.
None of the cases shown were sized prior to photos.
We had a lot of fun, never loaded at the range before, I weighed out 5 extra powder charges into fired cases and deformed the case mouths a bit gthen hand seated the 235 Speers nose down as a cork and it worked slick at the range. We fired the first load, popped out the primer with a pin, tapped by pliers, reprimed with a hand priming tool, squished the case mouth a bit, pulled the bullet from the charged, fired case, used a powder funnel and charged the new case and then finger seated the bullet about an 1/8" and used the leade to do final seat of bullet and get 100% consistency.
Thoughts and opinions?
Douglas