Yes I have the Heng Long recoil in a Tiger and a Panther. I modify the unit to snap back on fire and then gear drive return to fully extended. Very simple modification to the travelling block, and reverse the direction of the motor. Just got finished doing the mod to the stug. You can buy the recoils from Mato for about $8.00. Tie an LED into the HL ESC and you have a system that works pretty well. The stock stug firing sequence is out of order, with the light coming on after the bbl recoil. The simple Mods put everything right. Adding a "K" contact to your left stick on the transmitter can then get everything working in harmony. An upward blip on the left stick now creates an LED flash, gun recoil, tank recoil and IR cannon shot all at once.

Recoil gun $8.00
Contact switch $3.00
Superbright LED 3.00

About two hours of time and you are in business.

Also when I had the stug apart I was impressed with the enginerring that has gone into this. Metal bbl, and a real chinese puzzle of a mounting system, but rock solid and unique. Also the muzzle brake is threaded and screws off