I have a Beretta 682 Gold E Trap gun. The finish appears to be a high gloss epoxy of some kind. I adjusted the comb all the way over and it hits the back of my index finger when shot. I am going to sand off the piece that potrudes. What would you use to seal and keep the finish on that small portion I need to repair?

I bet you could hide a small spot like that using multiple coats of Tru-oil. Probably can find it a Walmart. Just dip the end of your finger in it and rub it in, let dry, then do it again until you get a close match to the original finish.