Have you ruled out the Chip McCormick mags being the culprit?
Many a feed problem has been cured with #47 Wilson 7 rd. magazines.
I wouldn't overlook this tip, if I were you.
There isn't much of a trick to polishing a feed ramp with a Dremmel Tool---properly used.
I use #4 Foredom compound followed by Rey Green Rouge for high shine. Polish both the frame and bbl ramps. All you're doing is removing tool marks and making it smoother. I use a felt, bullet shaped tip.
For deeper tool marks, I go with fine Craytex tips to start--then, as above.