This afternoon I took a few minutes, field stripped the Kel-Tec RDB, and took some pictures. The rifle's design is different enough so that I think you'll find them of interest. Clickenzee to embiggenate.
Slightly closer view of the barrel and bolt groups:
Bolt, bolt face, and extractor. Note the dual ejector plungers on the bolt face.
Piston head. It's a little hard to see but there is a weld blob on the top of the piston. Some earlier rifles left the factory without the weld, which leads to malfunctions.
The gas system.
Bottom of the handguard, showing the molded-in M-1913 rail. I have a Rogers Rail Light mounted.
Disassembly to this stage requires you to push out three takedown pins, plus one pin in the bolt carrier group. If you take down the BCG be careful. The firing pin is spring loaded and if you fail to contain it, it will launch itself several feet. (Yeah, it happened to me the first time I stripped the BCG.)