FUDDs come in many forms, as well. The original idea was indeed from the character of Elmer Fudd, with his cartoon hunting guns.
There's FUDDs who will declare that anything beyond their chosen year is okay to be banned. This varies from the 19th century to the 1960's...that anything beyond blackpowder isn't needed up to anything beyond their 1960's Marlin isn't needed. Whatever they think won't affect them.
There's FUDDs who think all semiauto rifles are killing machines and ought to be banned. They tend to shut up when you ask them if that includes the Garand, which is indeed semiauto and far more "lethal" than 5.56 AR! Surviving a COM hit with a 5.56x45 is possible. Surviving a COM hit with a 30-06 would be incredibly lucky.
There's FUDDS who want anything scary-looking banned...forgetting that their scoped hunting rifle is a SNIPER RIFLE on the nooz.
There are FUDDs who want all military calibers banned, even. As long as it doesn't affect their old thuty-thuty.
And, of course, there's FUDDS who even look down on other guns of their chosen sort. You see, you're supposed to show up at the clay range with a $25,000 engraved shotgun signed by Pietro Beretta himself. If you arrive with your plastic-stocked 870 with a rail on it, well, you must be up to No Good, and that sort ought to be banned, too.
The one constant is that they're all more damaging to gun rights than the antis are. Because they're willing to pretend to be gun-rights sorts, and then they throw everyone under the bus.