Good to see an old thread still alive. I've never had any sort of problem with my 4506 I bought NIB back in 1990, IIRC. The 4516-1, ditto. The only 3rd Gen pistol that gave feeding problems for whatever the reason was was a 4566 Tactical. I changed recoil springs, mags and springs but no dice. I reluctantly sold it at some point since it was going to be a house pistol.