= STOP right there =
Before you remove any material from feed ramp that could alter the feed angle, educate yourself and investigate why your pistol is not feeding.
Reliable feeding depends on several variables and chances are pistol manufacturer tried different things and ended up with the BEST variables before going to production. Change any of these variables and likely your problem will get worse not better. (If rounds not feeding is due to manufacturing pistol/magazine defects or wear, you should be looking at parts replacement and/or talking to customer service instead of fixing it yourself)
So let's investigate:
- Are you having issues with factory 115/124 gr FMJ/RN? (Pistols are usually designed to feed these reliably and if your pistol feeds factory FMJ/RN reliably, I would not touch the ramp)
- Has the pistol been field stripped and cleaned/lubed? (If not, do so and check feeding with factory FMJ/RN)
- Is there any manufacturing/machining flaws? (Most feeding issues with pistol revolve around the magazine. Are you having problem with all the magazines or just one? Any issues with feed lips, follower, etc.?)
- If the pistol is new, it may need "break-in" period before it is fully reliable. Recoil spring maybe stiff and lighter "target load" or white box ammunition may not be pushing the slide back far enough. You can lock the slide back until your next range session to help with recoil spring break in (More pertinent with compact/subcompact pistols with stiffer recoil spring/assembly)
- If the pistol is old, recoil spring may be worn and require replacement. How to check? Clear the pistol and pull the slide back and point the muzzle at the ceiling. Slowly return the slide until about 1/2" before going to full battery. When you release the slide, it should go into full battery without hesitation with full lock up of barrel. Any hesitation and I would suspect worn recoil spring and/or something dragging/friction inside the pistol that needs attention.
- If old gun/magazine, may need mag spring replacement and/or extractor/breech wall face cleaning. Once top round's nose bumps the feed ramp and case rim clears the lips, it's the magazine spring tension that pushes the case up to align with the chamber so the slide/recoil spring can push the round into the chamber. If the extractor has carbon fouling build up, case rim won't freely slide up the breech wall face and slide won't go into full battery.
I would do the things listed above first before suspecting feed ramp. (I have never polished the feed ramp of any of my pistols as clearly expressed by my bullseye match shooting mentor who taught me to do all gunsmith work on my match pistols with tighter chamber barrels).