{"product_id":"original-u-s-vietnam-war-inert-practice-m31-heat-anti-armor-rifle-grenade-trainer-dated-1964-66mm-2","title":"Original U.S. Vietnam War INERT Practice M31 HEAT Anti-Armor Rifle Grenade Trainer Dated 1964 - 66mm","description":"\u003cp\u003eOriginal Item: Only One Available. This is an excellent original U.S. Vietnam War-era \u003cb\u003eM31 Practice rifle grenade\u003c\/b\u003e, the inert training counterpart to the 66mm M31 HEAT anti-armor rifle grenade. This example retains its original blue training finish and legible period markings, including a \u003cb\u003e5-64\u003c\/b\u003e date for May 1964. It measures approximately \u003cb\u003e17 inches long\u003c\/b\u003e, with a maximum width of approximately \u003cb\u003e3 ¾ inches across the tail fins\u003c\/b\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eNot Available For Export\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eThe M31 HEAT is a fin-stabilized anti-tank rifle grenade designed in the late 1950s to replace the Belgian ENERGA rifle grenade which was adopted by the US Army and US Marines as an emergency stop-gap measure during the Korean War. Like the ENERGA, it has a nose-initiated, based-detonated HEAT warhead, but unlike the ENERGA, the mechanical impact fuse system is replaced with a less complex and more reliable piezo-electric fuse system which also allows higher angles of impact, up to 65 degrees.\u003c\/p\u003e\n\u003cp\u003eThis example has not been repainted and retains the original blue color very well, with all markings still legible. It is dated\u003cb\u003e 5-64\u003c\/b\u003e for \u003cb\u003eMay 1964\u003c\/b\u003e. The grenade is approximately 17” in length with a 3 ¾” base width, including the fins. The tail fins are a little bent with some paint loss, but that is expected with trainers such as this one, at least you know it was used by the military!\u003c\/p\u003e\n\u003cp\u003eThe live M31 contained approximately 9.92 ounces of Composition B surrounding a copper shaped-charge liner and used the M211 fuze. A piezoelectric element in the nose generated an electrical impulse upon impact, transmitting it to the base fuze to initiate the warhead. The system was designed to function at impact angles up to approximately 65 degrees.\u003c\/p\u003e\n\u003cp\u003eBy 1969, Army field manuals stated that the M31’s anti-armor role would increasingly be assumed by the M72 Light Antitank Weapon as sufficient quantities became available. The same manual lists the M31’s maximum effective direct-fire range against armor at approximately 115 meters, with a longer high-angle direct-fire capability.\u003c\/p\u003e\n\u003cp\u003eThe M31 was launched from service rifles using a muzzle-mounted grenade launcher and a special grenade-launching cartridge. The M7A3 launcher was used with the M1 rifle, while the M76 launcher was designed for the M14. I would avoid stating that the M31 was routinely fired from the M16 unless you have a specific manual documenting that arrangement, as the standard period launcher references center on the M1 and M14 systems.\u003c\/p\u003e\n\u003cp\u003eThis example is particularly noteworthy for its original blue practice finish, May 1964 date, complete 66mm M31 profile, and surviving period markings, placing it squarely within the early Vietnam War era and making it a strong representative example of U.S. anti-armor training equipment of the period.\u003c\/p\u003e","brand":"Original Items","offers":[{"title":"Default Title","offer_id":45921182744645,"sku":"ONSV26CNB184","price":195.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1524\/1342\/files\/ONSV26CNB184__01.jpg?v=1790953901","url":"https:\/\/www.ima-usa.com\/products\/original-u-s-vietnam-war-inert-practice-m31-heat-anti-armor-rifle-grenade-trainer-dated-1964-66mm-2","provider":"International Military Antiques","version":"1.0","type":"link"}