Polishing the internals. I've never seen obnoxious tool marks on the feed ramps of an AR. But polishing without abrasives can't hurt.
That's a good place to start.Ensure your weapon is unloaded and field
strip it. Wipe the chamber and all parts in the bolt carrier assembly free of oil. Leaving the upper and lower receivers separated
observe the feed ramps on at the base of the chamber. Put a pointed felt tip on
the proper Dremel mandrel and sparingly apply Simichrome on the feed ramps. There is no reason to use sandpaper on the feed
ramps so don't do it. We want to tweak, not alter.
Polish the feed ramps with the Simichrome and move on to jeweler's rouge. Don't spend a lot of time here, just polish to you can see
the ramps start to glaze. This reduces friction for those incoming bullet
noses.
Next, examine the rails on the bolt carrier. You should see areas on the rails at the base and to the side of the bolt carrier key that
appear worn and or shiny. These are friction areas. Smoothing here will
make everything work a little easier but again we just want to tweak. With the 600 grit paper go to work on any gouges and dings in
these worn areas. Don't spend a lot of time with the sandpaper because
you don't want to remove much metal. Go on to the Simichrome and rouge and get those edges to shine. Your bolt carrier should
move in and out of the receiver as if suspended on silicon bearings.
Turn over the bolt carrier and examine the bottom of the carrier. This is a high friction area as it contacts the top of the hammer during
cycling. Go to work with the sandpaper and lessen any marks, dings or
gouges. Graduate to the Simichrome and rouge and smooth the whole surface until it shines. Don't worry about a few marks. Just
better the worst of them.
Take a look at the bolt cam pin. This pin is also a high friction area. You'll notice several distinct wear patterns on this little pin. Start
with the Simichrome polish and go on to the rouge. The wear marks
should sparkle.Polish the back of the bolt behind the gas rings with Simichrome and rouge. This part moves in and out of the rear of
the bolt carrier during cycling and polishing in this area reduces friction.
The top of the hammer face, the surface that actually strikes the firing pin, is in contact with the bottom of the bolt carrier during
cycling. Lightly sand here with the 600 grit sandpaper, paying particular
attention to any tool marks at the rear of the hammer face, and continue polishing with Simichrome and jeweler's rouge.
Improving the trigger pull
As I mentioned earlier, military-style rifles are not known for their trigger pulls. Usually they are gritty and can benefit by taking the
roughness out of the hammer/trigger contact area. Please don't even think
about using sandpaper here. You can ruin your rifle if you use abrasives on the hammer/trigger contact area. Just polish this area with
Simichrome and rouge.
With your thumb on the top of the hammer, pull the trigger and ease the hammer to rest against the back of the magazine well. Look
down into the lower receiver and observe how the hammer assembly
goes together. Notice that the two arms of the hammer spring ride atop the trigger pivot pin. With your thumb on the hammer push
the hammer pivot pin out to one side with a small nail or similar tool and
remove the hammer. Pay attention to how the hammer pivot pin comes out and put it back in the same way.
Wipe the hammer/trigger contact area on the hammer free of oil. Polish the contact area with Simichrome and then rouge. Spend
some time here and get the contact edge/corner as polished as possible.
Don't bury the Dremel felt tip into the metal, keep the R.P.M.s up by letting the Dremel do the work. This area should be glass
smooth. Then smooth the trigger/hammer contact edge on the trigger
assembly. You should be able to polish this edge with the trigger still in place. Wipe these area free of polish and oil liberally.
Reassemble in reverse order of disassembly. Do not use force to seat the pivot
pin. You should be able to do this with finger pressure if everything is aligned properly. Check operation to ensure everything is
reassembled properly but do not let the hammer smack into the back of the
magazine well.
