My first impression of the MechTech CCU. The barrel and bolt assemblies are the heaviest components. They are held together by the recoil spring in the expansion manner rather than the typical compressive manner found onmost guns and rifles recoil design. Both units still had heavy machining lines when I received mine. They go inside the welded steel tube which isthe CCU upper. Slots on the steel tube are for spent case ejection on the right, and charging/bolt handle on the left. When pulling back with the bolt, you can press into the CCU upper to lock. Firingpin assembly and the extractor is housed inside the bolt secured by three large pins. Movement between the barrel and bolt has slack in it, from side to side. I’d expect it to be reliable with respect to dirt and sand. The whole CCU feels heavy definitely of substance. Mine has a mini-Quad rail in the front ($35), an M-4 collapsible stock($90), and a Tru-Glow Red Dot. They weigh in at 3.2lbs, front heavy. Compared to the aluminum and plastic Kel-Tec Sub 2000, the MechTech is definitely of higher quality. There’s a lot of steel,may be 3 lbs, in the barrel assembly and the bolt assembly. They will help dissipating heat from rapid firing. The fore hand guard is made of very thick and solid plastic. You can certainly drill holes to attach whatever else you want, like bottom rail for a fore grip. This hand guard is attached to the CCU withfour hex screws on each side. They also hold and align the barrel inside the CCU. MechTech says that you would only need to spray down to clean rather than disassemble everything. Prior to firing the firstround, however, I disassembled everything but the bolt and polished all sliding surfaces to remove machining lines, then treated them with Frog Lube. Everything glide easily and softly after that, without firing a round. As delivered, it is not a refined product. But if you like putting personal touches on your toys, you can definitely refine it. You will need acouple of hex wrenches to take down, a 5/32” for the bolt handle and a 9/64”(kind of odd). Be careful of the heavy recoil spring; it has serious potential energy being stretched out. Wear eye protection. Top of the CCU is a long rail, good enough for Red-dot. I don’t think you need a scope, but you can mount one. The CCU is a 25-75yrd instrument. I’d expect to hear stories of people pushing it to more than 100yrds but I’d use a different toy for thatkind of distance. Behind the rail is a small hole that exposes the recoil spring if you lock the bolt back. It’s a good place to drop some lube for the bolt to carry forward. My G20 frame goes into the slots designed for the four steel tabs, pushing it forward into a soft plastic barrier to snap in. Push it in again, while pulling the Slide Release tabs in the frame, which will release the G20 frame. There’s a GlockBlock, a ramp to aid chambering new rounds. It goes on top of the G20 block, has a tiny magnet to stay attached to the block. I attached the G20 frame and the mags, 15-round mag and the 30-round (capacity depends on who you ask) to dry cycle. They seem to load very well. Waiting for hot range time! Note: If your G20 is already tuned to minimize over travel with a Ghost Tactical connector, one with a stop-tab, then you may need to go back to a connector without such tab. The exact point your G20 releases the firing pin in a Glock Slide is likely different from that of aCCU, not by much. Mine would not release the firing pin, and since I don’t want to re-modify the stop tab on my Ghost connector, I just switched to a simple Ghost 3.5lbs connector. The bottom line is, I like this MechTech CCU already (without firing a round at this point). I say that from the standpoint of a Tinkerer who’d take down everything to make them function better. While I don’t have any skin in their business other than being happy to see them serve 10mm technology, I think they do a good job producing seemingly a good product, not refined butgood product at a good price. I spoke to them some, following up production progress. These folks are good people as far as I can tell. Now,on to firing live rounds.