Couple of questions

[stressed]

I wonder if a polyurethane buffer would help on the inside such as other weapons.

I am sure no one here "magnums" their luger with +P, +P+ or NATO rounds. 100 through 147 grain bullets will cause no more excessive recoil then a 115gr round, however the recoil can feel different. German army used 98gr through 124gr depending on load.