The TLR-2 should attach with a GG&G mount. I've seen pics of other forum members USPf's with the TLR-2 attached and most suggest using the GG&G mount. I'm pretty sure this is accurate, but if I'm wrong, someone please correct me.
No. The USPf and USPc both use a Universal Mounting rail which, despite its name, doesn't work with 1913 (Picatinny) mounting options (that's what's on the TLR-2 if I remember correctly). It's the same thing with the Surefire X series of weapon lights. The only ones that I know of that will fit without an adapter are the Blast modules and the HK UTL weapon light. I believe both of them will fit without an adapter as they were designed for the USP.
I think you might be able to use the Surefire mount since both the X series and TLR-2 use the same mounting rail (1913), but I'm curious as to how you'd like to mount the TLR-2. The Surefire mount if basically the same thing as the GG&G mount. Regardless, anything other than what specifically says "for use with HK Universal Rail" (ie. HK weapon light and Blast module), you'll need an adapter for it.
Just as an FYI, the adapter bolts around the Universal Rail and gives the USPf or USPc a rail right under the dust cover that will accept the TLR-2.
I'll see if I can find a good post with an example picture.
The TLR series by streamlight are an improvement over the polymer M series, which I believe was a joint effort between streamlight and insight technologies, some models are dual stamped. The TLR does not mount to the rails of the HK, as stated without an adapter. I own a GG&G, its very well made, in fact probably more durable that you would ever need it to be and if you want a mount, its worth the money. I installed it on my USP 40, and what I found was it was really hard to reach the on/off switch. I don't have this problem with the same light mounted on a G-lock. I believe the adapter lowers the light and moves it further forward than a firearm with a dedicated mounting platform. An upgraded feature is the screw on/off mechanism versus the pull down metal bar, slide forward release found on the M series, the TLR series also upgrades to an aluminum body, the only way to go if you mean to use seriously use the light. The TLR can be had in white light only for less than $100, and the TLR2 with laser module for about $240, both from LA Police Gear via the internet. Don't be price gouged elsewhere, my HK brother.
I just recently purchased a rail adapter and a TLR-2 for my full size USP 9.
I have not purchased the GG&G adapter yet, but the adapter I got was only $10 and works fine for now. I picked up my TLR-2 for $255 at a gun show (I know they are cheaper online, but figured I wouldn't have to pay for shipping... plus I wanted it right then!)
You might do a search on my name for topics started by me. I did a post a year or so ago showing how the three main adapters looked on pistols with the TLR-2, Pro-Mag ($20), GG&G (~$50), and Surefire (~$80). The GG&G IMO was the hands down winner and the best value for the money.
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