BUG of GangPlank

I've saw a video and tried by myself. if U have crit item of GangPlank, put a barrerl next to the tower, and auto-attack the barrel but when the mid of animation, turn your attack to the tower and it actually crit it. I tested it in 12/17 7:27 AM. it still work now as well. riot plz fix it because if they aced the opponent, GangPlank just 3 shot the tower and push the nexus in like 30 second by himself.