Sam,
It sounds like you are getting your money's worth out of that 300WSM.

As far as my RUM goes, the recoil pad helps some, too.
Although I can't honestly say I could put 40 or 50 rounds downrange at one session.
Probably more like 25 max.

"For joy of knowing what may not be known we take the golden road to Samarkand."
James Elroy Flecker