Now, I know in the movie, the Transformers are able to "transform" parts of their arms into weapons. We can see this with both Bumblebee and Optimus Prime...in some of the promotional art that is now out and about... However....even though arm cannons are great, to me, its just not "Prime." It works, if your name is Shockwave. It works if your name is Megaman. Hell, it even works if your Armada Red Alert, or a pirate named Cannonball...but Optimus Prime. Nah. Leader Class Prime needs a rifle. A gun of such magnitude, that it would make the Decepticons soil their metal. I found one that will work temporarily...so he;s the comaprison shot: Arm Cannon: Rifle: Now I can picture Optimus saying "Your on the wrong side of the blaster to champion that, Decepticon!"