The receiver cover is hinged at the front. Jim built it, there's no wobble. I gave it the first cleaning it had in 7k of mostly corrosive ammo, and it hadn't missed a beat in all that.
It's not cheap. But if you're looking for quality training, it never is.
Jim has a VZ kit he's going to build into a dealer-sample FA gun when he gets the time.
The AKS-74U isn't really comparable to the VZ. A better comparison would be Jim's FA AK-74 that I also shot. It's a beautiful rifle with virtually no recoil and extremely controllable in full-auto.
Note, it's not a "brake" on the -74U. The muzzle device is a booster to trap gas, fooling the gas system into thinking it's a longer barrel. It's increases the reliability. I was partnered with Jim in our two-day Fighting Rifle class. One of the drills had me shooting from the knee with Jim shooting from standing right over me. Each shot damn near made my brain rattle. It's a nasty little gun and I love it.
Getting to spend the last 5 days shooting and working on AKs with Jim Fuller has been an amazing experience.