Transformers Cybertron/WMG
The Transformers' physical weapons are largely irrelevant - It's all just Energon Power.
The weapons used by the Transformers are not based on their physical hardware alone, but on using the physical hardware as a channel for Energon power (the same stuff that gives them a Battle Aura ), much like speaking aloud spells which can be used through thought - it helps to concentrate them to their purpose. The more power you have, the more you can do with it. Scattershot is clearly shown firing laser blasts from the end of missile weapons. On the rare occasions he actually shoots his missiles as missiles, they always return/respawn to his body offscreen. Many such incongruities are displayed by many characters. The lasers/missiles are just blasts of Energon energy, and could theoretically be fired from the palms of the Transformers' hands, it's just easier (and Cooler) to use the physical weapons as a form of channeling, especially if they're a BFG. As the series' power levels increase, Transformers are shown to use Energon energy for purposes their physical bodies clearly are not capable of, such as Starscream's telekinetic rocks shortly after his Awesome Moment of Crowning. The most clear demonstration of this is Mega/Galvatron. At the beginning of the series, he can shoot lightning bolts of pure Energon power from his hand, which have the same effect as the series' lasers, with no visible weapon. Much later, during his final battle against Optimus Prime, Galvatron forms an impromptu Chest Blaster out of several pieces of armor intended to be used in a different way during his transformation sequences. These are inert pieces of metal with no weaponized properties (aside from their sharpness). He uses them as a Wave Motion Gun to use the most powerful "laser" attack of the show. In the same battle, later again, he is able to Ass Pull a giant sword clearly made of pure energy from nowhere. It's the same color as his aura. Go figure.
- This can also explain why Transformers so rarely show physical damage, and when they do it's a big deal, even if it's a single short circuit or a small amount of lost "flesh", like when Optimus Prime loses a wingtip and is seemingly nearly killed by it, or Scourge begs for death after "being defeated" when he is bruised by a very high-powered attack, or the Cybertron Defense Team lie dying with only cracks in their armor and still full structural integrity. Their armor is either augmented by Energon power, or protected by an energy shield of Energon power. When attacks actually deal damage to them, it showns that their shields have been overwhelmed by the attack, and in fact means that their "health bars" are nearly depleted. They also would have used up most of their power trying to block the attack, so even though when the attack finally got through it did minimal damage, the real damage was done before the attack struck.