Streamlight HL3

So I picked up a Streamlight Protac HL3 a while back and was pretty pleased with the output and reach. Thought it would work very well as a rifle light. Well, I spoke with Streamlight and they wouldn't confirm anything just recommended one of their lights with the integral weapons mount. Well, is there any particular build differences between the Protac HL-3 and their weapons light, the Protac Rail Mount 2? If anybody has the rail mount 2, do you mind breaking it down and posting a pic or two? I've been running a Polytac on one rifle for a while now without any troubles and can't imagine the Protac would be any different. I don't plan on running it too hard, just 5.56 and .300blk.