Can someone answer a question for me,I good was just on Tank Modellbau.de and they have a video for the guns showing a recoil with no jerk with a good muzzle flash, good for heng long tanks and the RRZ system. what is this system, i have not heard of this one. and has any one done businesses with this sight.

The RRZ is the Asiatam recoil unit. The site you were on has fixed and 2 piece barrels for the recoil movement. Very good prices and looks like a quality item IMO.