Here you go MM....... Will post more pics later but this is the start. It would be much simply for you when you get the actual recoil barrel.
Original HL Sherman BB barrel:
Slide in connector to extend the barrel:
With the extender:
Complete barrel extended and connected to BB slider:
Full recoil position:
Normal barrel position prior to and after reocil:
There is a slot at the bottom of the BB barrel to lock it to the mantlet, so it can act as guide to remove rotational movement from the servo. I don't know if the stock recoiling barrel also has the slot, but you just have to be careful to line up the barrel properly when you install it, or simply sand out the slot in the mantlet. I am leaving it in and it causes any issue I will sand it out of the mantlet.
More pics later after installing the servo.
MicahelC