PSC American Heavy Weapons Set

This is an interesting little release from the Plastic Soldier Company (PSC) to complement the US Infantry with the miscellaneous variations on heavy weapons (mortars and machine guns) that the US Infantry hand in the Second World War (see below):

These include three each of the following (crewed):

• M1917 Machine Gun
• M1919 Machine Gun
• HMG M2 Browning
• 81mm Mortar
• 4.2 inch 'Chemical' Mortar
• 60mm Mortar

Interesting and "wacky" stuff, especially the 'Chemical Mortar' thing? What's that then?