My Urutau was a big hit at the range today. ROs and shooters alike were all very interested in the build and how it performed. I've been slowly working to get the firing pin length dialed in and I think I'm finally getting close. I didn't run a lot of rounds, but it ran the two 20-round factory CZ mags and the two 30-round ETS mags I brought without a single failure. Some slow-fire, some doubles, some Bill-drills. I even ran the last 30 rounds with a 3D printed can (OKB-69 Khrizantzema). Note that this is with a remixed lower receiver since the ETS mags do not properly fit the lower in the official release. If I have another successful range session with this lower, I'll release it.
Sweet build, thanks for the quality info as well!