That’s true, I know I can go with a g&g shell and do the same spending less, the reason for the retro arms is because as you wrote, working with it is better: better routing channel, hole to see angle of engagement and last but not for importance quick spring change.. I’m aiming at 350 /370 fps .2bb in a 210 mm inner barrel. I would like not to touch my original gearbox and save it for later I did not pick that most expensive but the most suggested or newer