I’m not actually in the assault bezel market, but for those who pick up an UltraFire C1*, replacing the plastic retaining ring may be necessary.
This might do the trick:
http://www.manafont.com/product_info.php/31mm-3petal-stainless-steel-crown-head-for-led-flashlight-p-6020
It replaces the plastic retaining ring. I’d probably put it on the saw or dremel and cut most of it off, then try and grind it flat-ish with small crenelations like I like. DX also carries a C1 that has an XM-L + Assault Crown for $22, but it’s only single-mode and I think that may just be too bright…
*(Such as the super-inexpensive XM-L T6 models Ultrafire has now: http://www.dealextreme.com/p/ultrafire-c1-xm-lt6-5-mode-510-lumen-memory-white-led-flashlight-with-clip-strap-1-18650-55237)