Found a way to bore a Surefire with common tools...

I have found a way to perfectly bore flashlight bodies (or at least a Z2) with nothing but a ratchet, the right size extension (sorry, calipers broken right now and I can't find my ruler, will edit as I find out what size), some 6" self adhesive wet/dry sandpaper discs (I'm using 200 grit though I wish I had 100 grit to start with), and a whole lot of time on your hands.

Step 1 - Attach extension onto ratchet
Step 2 - Wrap sandpaper disc onto extension
Step 3 - Run under tap water and ratchet away, taking time to change from tail to bezel end. The sandpaper expands with the water and even with 200 grit, I'm getting a nice smooth texture.

I'm not quite finished but it is definitely working as I can almost fit a Westinghouse 18500 into it, but not anything else. It is painstakingly slow and you can expect to go through about 10 sand paper discs during the process. The only reason I'm doing it is that I got a chewed up unfinished Z2 from my old boring guy and I wanted to smooth out the inside... then I got a carried away .... I will post pictures when I'm done... it's looking good so far but it's been about an hour and a half of ratcheting...

I was able to do pretty much the same thing but with a power drill. I also found some sanding cloth . It last a lot longer than sand paper. Plus instead of running water ,I fill the sink and dunk ever so often. Took me about 3 hrs to do a 6P.