To the poster above...for smaller parts like you mention here, do it by hand. Way easier to get to the smaller grooves and holes
That's what I do atleast..
On a separate note:
Did a UL-back here a few days ago.. Think the result was pretty nice..
I left the Dye ul-lettering and the ridges + logo on the barrel dust black (the original color)..
And polished up the rest using increasingly fine sandpaper
Took a while..but the result was reward enough for me..
The image quality isn't the best.. But I assure you, it is SHINY
And, you might aswell admit it right away.. The "leaving the logo, lettering and ridges dust black = AWESOME.
I haven't seen it done before, but always figured it would look GREAT..