I figured you guys would appreciate this. Cut 15mm off the bottom and rethreaded it to use the stock cap to use an 18350 battery. I can use the extension cap to use an 18500 too.
I put a P+18350 to the left and a P+18500 to the right with a standard Provari for size comparison.

I put a P+18350 to the left and a P+18500 to the right with a standard Provari for size comparison.