The 7 WSM is unique For the WSMs, but the 325 Wsm Can be made from the 300 WSM
When you move a shoulder very much It can cause problems(As you are finding out), Except
when fire forming and the case cannot resist the pressure.
You can bump the shoulder after it has moved forward enough to cause problems but that is
normally only .002 or .003 Thousandths.
Long tapered shoulders (Like the H&Hs)can be moved back with some success because they
have 8+degree shoulder angles but when you get in to the 30 to 40degree shoulders that's
a different beast.
The cost of bullets,powder and primers are almost the same price as the brass, so the trouble
and barrel life are not worth it in my opinion.
Just buy new 325 brass and have fun.
J E CUSTOM