Buffing a dull shell?

[DynaMight]

Hi guys

My shell is black & after almost 9 months of us its starting it look a little dull, especially on the sides.

I've tried a few things. I tried a some wet sand paper, but only upto 1200 as I didnt have any higher but didnt make much difference, and a form of T-Cut but didnt seem to make any real difference, also tried a metal polish but no effect. Lastly I tried a dremal with a small buffing wheel, this worked the best but was a thin line between buffing and marking the surface

Any suggestions on how to get some form of gloss/shine back?