I generally follow an "everything you need, nothing you don't" philosophy when I choose equipment. When it comes to hand guards the "tube with a rail on top" style works perfectly for me. I don't have a use for about 75% of the rail space on a traditional quad rail and I don't like having useless weight on my carbines. I have a few of the TRX Extreme rails and finally managed to strip one of the threaded inserts. Troy replaced it with the new and improved version, the Alpha rail, for free. The Alpha has a unique locking system that I think is pretty ingenious. It uses three clamps that lock the rail into a standard USGI barrel nut. Below is a short review with some details about how the rail installs.
Here are the locking nuts and bolts. They're steel and the screws are made by YFS. I didn't bother to measure the threads but they're pretty beefy. You'd have to be really trying to strip the thread on this one. It will hopefully become more clear below but basically the angled portion pushes forward against the barrel nut while the raised tab locks the nut into the rail. There's a groove in the rail itself that the barrel nut rotates into and locks the rail to the barrel nut.
Here you can see where the locking nuts screw into the rail and the groove where the rail itself interfaces with the barrel nut. I used Vibra-Tite for this application to allow myself to periodically remove the rail without having to strip and reapply blue Loctite. The Vira-Tite is appled and allowed to dry before installation giving the used plenty of time to work with the part.
There's a little protective coat of oil so I degreased and dried them.
Then I installed the three locking nut assemblies into the rail and the rail accessories I wanted to use. This is going on an SPR type build so I added a short section of picatinny for the bipod and a Noveske QD sling mount. One of the main reasons I like the Troy rail over some of the alternatives is that availability of aftermarket accessories that direct mount without having to attach a whole rail section.
The Alpha rail slides over the barrel nut and is rotated into alignment. Notice the anti rotation tab.
I used a carry handle for alignment before torquing the locking bolts down to 72 in-lbs each. I don't think it's critical to achieve perfectly identical torque on each bolt but I have the tool so I thought I might as well use it. If one were to just tighten the bolts down with the included allen wrench you'd achieve the same thing that I did with the torque wrench, namely snugging the rail against the barrel nut.
Here you can see how well the Alpha rail lines up with the upper receiver rail.
And here's a gratuitous shot of the final product.
Overall I'm very impressed with the way Troy designed this rail. The locking system is very well executed and best of all uses the standard USGI barrel nut. The parts appear to be very rugged with a steel bolt screwing into a steel nut as opposed to the old system of using a threaded insert in the aluminum rail. I don't see how one could reasonably strip the threads on an Alpha rail but even if it happened you would just have to replace the bolt and nut which are separate pieces from the rail.
The TRX Extreme was one of the lightest rails on the market and, though I haven't weighed it, I assume the Alpha rails are around the same weight. I don't have huge issues with the rough surface. I've heard it described as a cheese grater but I don't think it's that bad. If I'm shooting a lot I usually have gloves on and if I was in some kind of defensive situation I think it would be the least of my worries. I'm eventually going to pick up some of their new Squid Grips and see how those do.