It guards your hands.
You can also mount stuff to it, cut it up to make it fit on a gun that it was never intended to fit on, paint it.... or in our case, do all three.
As with the Space Cowboy Gun, much of the custom work on this cyber-gun is in the handguard. I'm starting with Midwest Industries 12.5" MCX Handguard, and planning to cut the back off, file down a couple of the picatinny rail pieces, and drill it to so it attaches to the front sight block. Then I'll paint it.
Before I get to hacking, enjoy some pics of this fine rail. Please forgive me Midwest Industries for what I am about to do to your handiwork.
I selected this rail for 3 main reasons:
Its shape. Compared to AR-platform handguards it's tall and thin. AR handguards are typically circular or hexagonal. I need more space below the GP100's barrel than AR handguards provide and I didn't want this gun's handguard to be way wider than the cylinder. MI MCX handguard is ~2.6 inches tall and ~1.7 inches wide. Enough to get a small scout light under the barrel without modification and just about as wide as the revolver's cylinder.
Its shape. I know this is the same point as above, but this is about the shape of a specific part of the handguard - the top. I wanted a handguard that has ~7 or so inches of the top connected. Other rails that fit the taller-than-wide description above are for shotguns, AKs, or lever action rifles and they have an open top. Since the top is going to be where the handguard attaches to this futuristic revolver, I want it to extend from the red dot mount to the front sight block.
M-LOK is space approved. I checked.
A couple others handguards that were runners up. These would probably work on a space gun, but I think the MCX rail was the right choice for this build.
Texas Weapon Systems Gen 3 Short Top Handguard. This one may have worked as well, but likely would have required more cutting on the inside than the MCX rail. AK rails are less free float-y than AR style handguards (including the MCX). This handguard is interesting though becuase it is a top and bottom piece bolted together. It may be useful on a future build.
Midwest Industries ACR MLOK Handguard. This one is very similar to the MCX rail that I chose. The key difference is the amount of the top of the handguard that is connected. This ACR rail only has the front ~4 inches connected.
Enough yack yack, more hack hack!