The M40 recoilless rifle is a lightweight, portable, crew-served 105mm weapon intended primarily as an anti-tank weapon. The weapon is commonly described as being 106mm, but it is in fact 105mm; the 106mm designation was intended to prevent confusion with the incompatible 105mm ammunition used the failed M27 recoilless rifle. This one is mounted on a M38A1 Willys jeep.