WW2 Luger ammo, Cont.

Using factory ballistic differences between 7.65 and 9mm Luger ammunition, the 9mm has 12.3% greater muzzle energy and 22.6% greater
impulse over the 7.65.
Military 9mm ammunition has at least 100 fps greater velocity.
The 7.65 Luger recoil spring needs to be lighter.
In using heavy 9mm loads in a formerly 7.65 Luger, it would be wise to replace the recoil spring with a heavier one to avoid beating the gun up unnecessarily.
Wolf Springs makes them with heavier spring rates. Use the heaviest spring your Luger will cycle reliably with.
Lugers are very strong and there's no way a toggle will break loose and come at you.
The weak link is in the striker design. A grossly overpressure load will blow the primer (pierce) and launch the striker rearward (not withstanding pressure relief grooves) with enough force to break out the striker spring retaining notch in the breechblock rear. It will tie up the gun but not injure the shooter.
I've read but haven't experienced that the extractor can also blow out should the case let go.