In the Deadliest Warrior article, it mentions that the AR can't have a four-position selector.
But according to my copy of the AR-15/M16 Source Book, CAR-15 variants used in Vietnam and even XM4 prototypes had four-position selectors.
Which is it?
I'm asking because I'm doing some corrections to weapon articles on the Resident Evil Wiki site, where the M4 carbine has an entry..