XM177E2 with XM148 - 5.56x45mm/40x46mm
XM16E1 with XM148 - 5.56x45mm/40x46mm
The XM148 Grenade Launcher was a prototype 40mm underslung grenade launcher designed to be mounted to the M16 series of rifles, by Colt Firearms. The XM148 did a series of field trials, but it was never formally adopted nor fielded in great numbers, since the U.S. Army decided upon AAI Corps' 40mm Grenade Launcher, which ended up being the M203, which is the current 40mm Grenade Launcher used by U.S. Military forces and their allies (though is being phased out in U.S service by the Heckler & Koch M320). It is extremely unlikely that any actual XM148 will appear in any movie or television show, since most existing examples are in museums (except for a single genuine XM148 in Mosfilm studio guns collection), however it has been depicted via artist work in Anime or Video Games. Mocked-up 'copies' of the launcher, made out of aluminum and plastic by propmakers have been seen (but not verified) in B-movies.
The XM148 grenade launcher and variants can be seen in the following films, television series, video games, and anime used by the following actors: