I was recently told that Surefires (specifically, the G2X and 6PX) are poor choices for a weapon light because there is no spring in the head, so the batteries are in direct contact with the board, making it a potentially unreliable connection under fire.
This is a somewhat rhetorical question, as I myself and a couple guys I shoot with have been using G2Xs on carbines for some time without issues. With that said, I wanted to post this up on a few forums for more info. A poll has been added to collect feedback.
While these are not by any means the most ideal weapon light out there, they are tough and affordable. I've seen dozens of others running the very compact Surefire LED flashlights the guy was speaking of on rifles of all kinds, so there should be a sufficient sampling of users to gauge the legitimacy of that statement between the different forums.
Thanks for your feedback!