This isn't really too much of a modification rather than stumbling upon something that works. The tank barrel pops off and fits on the cannons. The 2nd pic down from the top: You have to slightly shave down the sides of the little mini cannon so it stays flush. The triangular shape makes it want to pop off as you can see. The 3rd pic down, the sight/tab on the cannon fits inside the hole on one side or the other of the barrel quite securely. Now Guzzle has something of a tank/gun/sniper/rifle. "What"??