I have polished aircraft windows and canopys using an orbital sander with micron rated buffing pads and water. (Wet sand) finishing it off with 3m polishing compounds. Perfect results. However these micron discs are hard to find outside of the aircraft industry. Hint hint.....you have a lead on...
What trigger do you have in it? Glock make some triggers that imitates a DA revolver with over 8 lbs of pull. You may be happy changing the connector from a stock 5.5lb or try one of the many 3.5 lbs on the market. I don't think one is better than the other , just personal preference.