Mike: Those little burs are the result of someone using undersized wedge screw drivers. If you do play with gun screws and do not already have "hollow ground" turn screw tips, they are well worth the investment. A good set will have the right tip to completely fill the length of the slot and completely fill the width. Unless that is done, one risks twisting the driver out of the screw under torque and there's your bur. Do it a couple more times and you have the really buggered screws we have all seen.
Also, since you only have annoying tiny burs, a brass punch or maybe even a hard nylon punch might fix it for you with minimal likelihood of causing damage anywhere else.

Tap gently !!

Cheers,
Jack

I once had the opportunity to watch Jack Haugh reshape and restore a horribly mangled and burred flintlock top jaw screw using just a hammer to move the metal back into it's original form. He was using just a small ball peen hammer with a head which was not much over about 1 1/2" to 2" long on a sort of slender handle 8" to 12" in length. He did also have laid out a few round slightly concave shaped hardened drifts, but I did not see him employ them. While I watched the metal slowly, sort of magically, move back into place he explained that you really could not do this with a bigger hammer, but that the secret was in multitude of patient blows from a hammer with just enough weight to coax along a little metal with each hit. He also made the point that the strikes were actually directed at just enough of an angle to move the material in the direction desired. The screw was secured in a very substantial vise with safe lead jaws which meant that all of the energy of the medium sharp blows was delivered and concentrated at the small point of impact, and that no energy was lost to any movement of the screw itself. To prove this point, he at one point when adjusting it in the vise handed me the screw so I could feel the heat that had built up in the area just being worked. At another point, although he did not need to do it with that screw, he said that another trick to keep in mind when rebuilding old screws was to sometimes take the time to file up or grind a piece of steel into a small blade of a thickness to be snug in the screw slot which could be slipped sideways into the slot and rest firmly on its bottom. One end of the blade should be contoured to the radius of the dome of the screw, and the other be large enough for your other hand to hold and move the blade in the screw slot while working the hammer. The purpose of this tool is to prevent metal from being moved into the slot where it later might only be removed by filing which would mean the loss of original metal. His final comment was that if a screw was to have the engraving restored it was probably a good idea to anneal it before raising the cuts so that the graver tool would not hit hard and soft spots while working the design around the head of the restored screw.