This is a ridiculously easy way to improve your 10/22’s trigger without buying a $50 aftermarket hammer or anything. You can literally do this with a little J.B. Weld and some files, although it clearly doesn’t hurt to have a rotary tool.
It looks totally Bubba but even a Bubba can see how this works. It builds up the hammer so that there is less material in contact with the hook, which in turn requires less force to actuate.
The reason why a couple thousand rounds will lighten the trigger is that the hammer’s engagement surface gets polished by metal-on-metal contact. If you want to speed up the process just polish it manually.