The BARC 4 is not designed for independent control of the cannon. My suggestion is to run the elevation control independently through the receiver on a proportional 5th channel. Otherwise leave it stock and let it cycle through the HL cam set up, like it was designed to do. Independent control of the bbl elevation is not really possible just using the 4 standard channels, for the reasons you have mentioned.. Remember it has never been advertised as independent control of elevation.

The BARC 4 because of all the trigger points is much more sensitive to trim control. You need to have cannon elevation trim fully engaged, unless you have a programmable radio where you can set the sub trims. Once trimmed out the turret will run smoothly.

True plug and play has its limitations when using the stock tank components. When you choose to get creative and work outside the lines for what this was designed for then things can and do crop up that require special measure to work through. Perhaps a servo adjuster can be added to give you the delay you require so that when you fire the cannon the elevation servo does not move.

I wired up a DPDT center off toggle switch on my radio. Flip the lever up fires the cannon, down fires the MG. Pretty simple fix that gives me a switch on the radio for weapons fire. Again servo elevation is best done with a complete separate proportional channel, as per my recommendations.

What radio are you using?

Cheers


Dan