WWII Tech Pubs Briefing

Written by
Duane Godwin

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Overview

The No. 36M grenade evolved from golf club designer William Mills’ Grenade No. 5, the famous Mills Bomb of World War I.

The No. 5  became the Grenade No. 23 after obtaining a tail rod that allowed it to be fired from a rifle.  In 1918, the genade was modified to accept a 2.5-in (63.5-mm) detachable base plate that would let it be launched by a rifle discharger cup.  Although this weapon was officially redesignated the Grenade No.36, popularly it was still called a Mills Bomb.  A quantity that were specially waterproofed and prepared for issue in Mesopotamia were designated No. 36M.  While the Nos. 5 and 23 were removed from service in 1918 and the No. 36 was declared obsolete in 1932, the No. 36M remained in service as the British Army’s standard grenade.

The No. 36M anti-personnel fragmentation grenade had a cast iron body weakened by longitudinal and transverse grooves to assist in fragmentation.  It used the French Bouchon fusing mechanism that relied on an “igniter set”, a .22-cal (5.6-mm) rimfire cartridge, a short length of safety fuse, and a detonator.  Originally, the fuse provided the lengthy seven-second delay necessary for use as a rifle grenade but combat experience showed that seven seconds was too long a delay for thrown grenades and in 1940 a four-second igniter set was developed and issued.  The seven second delay was retained for rifle launching.

The No. 36M was a defensive pattern grenade whose shrapnel could kill within 80 yd (73 m) of the detonation point.  The thrower had to be behind cover or immediately had to lie prone after throwing.  In a bunker or other enclosed space, the Mills Bomb was lethal to the point of overkill.

Despite its habit of erratic fragmentation - large pieces were often flung more than 100 yd (91 m) - the No. 36M gave sterling service throughout World War II and beyond.

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Specifications