When the lights stick out past the muzzle you'll eventually burn the top of the light. It just leaves a discolored area but so far has not eroded the surface.
Each shooting session builds up powder residue on the lens and lens cap. That'll wipe off with a clean rag/cloth. So far I've not really "seen" any damage to the lens, just a build up you have to clean off after each shooting session.
If you put/wipe a drop of oil on the lens before shooting, cleanup is a breeze, and you can prevent most of the buildup because it wipes right off afterwards. I sometimes forget, though...
Late to the party as usual, but I like my TLR-1:
CZ P-07 and Streamlight by
Staufhammer, on Flickr
CZ P-07 by
Staufhammer, on Flickr
