The HM-3 is a submachine gun of Mexican origin chambered in the 9mm calibre and, since 2011, in .380 ACP caliber for private security forces.

It is a lightweight weapon of reduced overall length achieved by largely extending the wrap around bolt forward around the barrel.

The HM-3-S SHORT is almost identical, with the exception that the barrel is shortened and therefore measures only 12.99 in (21.06 in with extended stock).

The HM-3-S BULLDOG (also called HM-3-S Mini) is a miniature version of the weapon, especially designed to be carried by motorcycle police and bodyguards, and measures only 10.8 in (19.3 in with extended stock) in length and weighs 2,827 g (6.2 lbs) with a full 32-round magazine.

[3] Since 2011, Productos Mendoza has manufactured a variation of the HM-3-S that shoots a .380 ACP caliber round.