Just got this guy, he's better than I thought he'd be. Did not like the alt mode cannon hanging down behind him, so I bent it like the Leader figure, around his waist under his right arm.
It's not as elegant as the Leader's solution, but it works IMHO. I just cut the barrel at the middle of the large section, and glued a suitable peg into the section that stays in the turret. Then the other half fits onto that peg in both modes.
EDIT- forgot to add something important: the cannon barrel is mounted to the black panel on his back by a rivet and a large tab that is part of the cannon barrel. You have to cut that tab flush with the black panel to let the barrel turn separate from the rest of the back kibble.
I also trimmed the inner edges of the arm blades so they can fold back over the arm gatling.
Comments are welcome!