I have this fetish for taking things apart, polishing them up with a dremmel tool and filing off any burrs.

Not being much of a gunsmith it is the only thing i feel I can do in some cases that will help some without risking damaging anything.

Just wanting to get some input on the matter;

Can I ever do any harm polishing moving parts with a cotton buffer and some polishing compound?

Yes you can do harm. removing to much or the out side harding of some parts well leave you with a very worn gun. Removing burrs carefully can help smooth a action a lot. I hardly ever use a dremil tool for such work to easy to go to far to fast.

Be careful start out very slow only remove a very little at a time.

The biggest problems with "power tools" is that they work really fast!

Many parts in weapons rely on their squareness and/or sharp edges in order to function properly and it is really easy to round-off those edges when polishing with a power tool. At least that has always been my experience.

I have always found Arkansas stones to be much easier to control for polishing parts and the fact that they do work so slow is a plus...for me anyway.

Surface hardening (despite the name) penetrates into the steel to a certain depth which varies depending upon the process and technique used and unless you really get carried away there is little chance you will soften a part through careful polishing. The operative word being "careful!"

I would be far more worried about changing the geometry of the part rather than ruining the hardening.

Rick