Wrecked brass with only 42 grains IMR 4350 in mine and 117 grain Hornadys : Post-64 Model 70 with a heavier barrel. Came apart at web after four loadings.
My first guess is you're oversizing the brass.......
Nope, WW brass sucks. And, the rifle chamber is tight. Loads too hot as shown by good results with other brass offerings.
Best results with the 4831's since.
