There were two set screws that were stuck inside one of those TDI rubber grip covers. It looks like they are used; set in appropriate holes to fit either a milled or stamped receiver. Once I put them in, the handguard locked up tight. I can only assume that's what they are used for...since no holes were left after I installed everything. First time I ever put something together without having left-over parts!
Man, this thing is S-O-L-I-D. I'm a bit of a gun & gear snob...so if I'm impressed, that says a little bit about a product. Installation was a breeze (once I found the set screws) and the entire assembly is pretty intuitive. The machining is second to none, and pretty much on par with the likes of SWAN and KNIGHTS (at least from preliminary inspection). I know...some would consider that blasphamy, but I've had exposure to multiple rail systems and own a S.I.R., and this rail system is definitely within the same ball park.
My only chief complaint is that the top rail could be about 1/2 shorter. This would allow me to field strip the Bulgie without having to seemingly dissassemble the rail system. I'll try and write a range report after I take it to the range this weekend!
~Mickey