I know that servo recoil units are nothing new. But I was thinking of Dean's M10 destroyer kit and how to finagle a servo system into it...
I gather that direct servo linkages are susceptible to having your tank barrel run into things. (aka breaking the servo link from impact.)
Even if a linkage or a sliding post style, they require the servo to power the barrel back into battery.
The top shows how you can bury a servo in an open turret concept like the M10 kit. You can hide return springs in the "recuperator(s)". You may even just be able to push against a pin/protrusion on the barrel itself instead of using a push rod.
The bottom one would be a cable pull version. You could use a spool if needed. Like only usable on long barrels as you would want to have the cable pull along the barrel axis as much as possible. (Spool would likely work better now that I think of it.)
Just a couple thoughts. Any comments?