Those higher Amperage VESC's have Sold out for now. In short though VESC's are good for drive or lifters but not for spinning weapons.

To get the most out of what you have, set the ERPM to 80'000 and raise your max current to allow for bursts at start up, that should help it get going. Regular VESC's are not designed to run motors greater that 2Kw, and our up rated ones only just handle our 3.7Kw motors.