I'm not a 'smith but this is a very simple do-it-yourself project.
You have two choices - get some 600, or better yet 1200 grit emery paper, and polish the ramp with a piece wrapped around your finger. Finish with a cloth and some Flitz or jeweller's rounge.
Second choice is the Dremel and a cone-shaped felt bit. Put some Flitz or rouge on and LIGHTLY polish the ramp.
No matter what method you use, go slow and light, and do not remove metal, or re-shape any angles. Be extra careful if you have a lightweight aluminum alloy frame, as the feedramps are aluminum (soft!) with an annodized coating of steel over top (hard). Remove the steel anodizing, and you'll wear out your ramp in short order, especially if you shoot HP ammo.
I used several thicknesses of paper towel wrapped around my index finger, moistened the towel, dipped it in 600-grit abrasive powder and rubbed the feed ramp until the surface felt glass-silk to touch. I used no more than 20 strokes, probably less. Minor light machine marks are still visible.
You could also use a Fine Cratex bullet bit in a Foredom or Dremel. If you cut by hand, I recommend using a mandrel of some sort to back the abrasive, perhaps a dowel or rod of some sort. It'll keep you from inadvertently altering the geometry of the ramp or corners.