One of the major advantages of jeweling steel is that the surface retains oil better than a polished surface, making for reduced wear and increased rust resistance.
Small Compressor
Check the pawn shops, they usually have some and they are often a good buy. Remember that oil-less piston-types are very noisy and small diaphragm-types are quiet but most produce less pressure than piston-types.
Delaware Lower
I'm not an expert, as this is my first AR, but mine is very nicely finished everywhere you look. All functions seem good and it is a very tight fit to my CMMG upper.
Is anyone doing good bolt mods in the Indy area? Mostly I want the lower rear radiused and maybe the firing pin pinned-down in the front for additional reliability. I might want jeweling if it is really good or I might want it blackened because everything else is black on the rifle.