just for information for anyone facing this type of problem - i think i have it solved.
I had replaced the recoil assembly on this gun with kahr parts and it didn't solve the problem.
I ordered some springs from wolf gun springs - the heavier set designed for the pm 40. After installing these heavier recoil springs, the gun fired without a glitch. Fed 100 rounds through it without a problem.
Clearly, brute force won out on this one. I'll still try polishing the ramp but it's now working reliably!