I am trying to remember the name of a character. I've looked around on Wikipedia and a couple of other places but I haven't seen anything.
I think he hung out with X-Factor for a while, but I don't think he ever "joined" the group. This was the Havoc / Polaris / Strong Guy etc. era of the group, and would have been around the time that Rob Liefeld was taking over the New Mutants, because that's about when I quit reading.
This guy had white skin and wore a brown vest and sunglasses. He was some sort of shapeshifter and often turned his arms into big guns.
(I was thinking about him because I was explaining to someone that one of the reasons I quit reading the X books [and most of these reasons I blame Liefeld for] was that every team, it seemed, added a member whose mutant power involved carrying big guns. Cable, Bishop...and this guy, although apparently he never really joined. But it sure seemed like he was about to when I gave up.)
Last 5 movies seen: Wedding Crashers - Broken Flowers - King Kong (2005) - Grizzly Man - The Wild Parrots of Telegraph Hill
Random, a mutant made of morphing protoplasm, which acts to counteract any force or mutant ability directed at it, can expand his mass and strength, and can be fired as biomatter projectiles. It turned out that he was just a teenager who shapeshifted to make himself look tough. I'm pretty sure he's dead now.