I read what drwhou2 had to say about the give item cheats, and have yet to try them, but got to thinking the item names ending in opt (example : springfieldopt) should be rifles with optics, as detailed in the inventory screen in-game, rather than ammo magazines.
I arrived at this conclusion because the only ones in his list that use the opt suffix all come as rifles with optics (scope) in various missions in the game. Hope this will alleviate some confusion.