| Mills bomb | |
|---|---|
 Mills bombs. From left to right : No. 5, No. 23, No. 36 | |
| Type | Hand grenade |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1915–2021 |
| Production history | |
| Designed | 1915 |
| No. built | over 75 million |
| Variants | No. 5; No. 23 Mk I, II and III; No. 36 Mk I; No. 36M Mk I; No. 36 Mk II |
| Specifications | |
| Mass | 765 g (1 lb 11.0 oz) |
| Length | 95.2 mm (3.75 in) |
| Diameter | 61 mm (2.4 in) |
| Filling | Baratol |
Detonation mechanism | Percussion cap and time delay fuse: 7 seconds, later reduced to 4 |
"Mills bomb" is the popular name for a series of Britishhand grenades which were designed byWilliam Mills. They were the first modernfragmentation grenades used by theBritish Army and saw widespread use in theFirst andSecond World Wars.
William Mills, ahand grenade designer fromSunderland, patented, developed and manufactured the "Mills bomb" at the Mills Munitions Factory inBirmingham, England, in 1915.[1]
The Mills bomb was inspired by an earlier design by Belgian captain Leon Roland, who later engaged in a patent lawsuit.[2]
Col. Arthur Morrow, a New Zealand Wars officer, also believed aspects of his patent were incorporated into the Mills Bomb.[3]
The Mills bomb underwent numerous modifications before being retired from service.
The Mills was a classic design; a groovedcast iron "pineapple" with a central striker held by a close hand lever and secured with a pin. The heavy segmented bodies of "pineapple" type grenades result in an unpredictable pattern of fragmentation.
According to Mills's notes, the casing was grooved to make it easier to grip, not as an aid to fragmentation; and it has been shown that it does not shatter along the segmented lines[citation needed].
The Mills was a defensive grenade meant to be thrown from behind cover at a target in the open, wounding with fragmentation, as opposed to an offensive grenade, which does not fragment, relying on short-rangeblast effect to wound or stun the victim without endangering the thrower with fragments, which travel a much longer distance than blast.
Despite the designations and their traits, "defensive" grenades were frequently used offensively and vice versa. A competent thrower could manage 49 ft (15 m) with reasonable accuracy,[citation needed] but the grenade could throw lethal fragments farther than this. The BritishHome Guard were instructed that the throwing range of the No. 36 was about 30 yd (27 m) with a danger area of about 100 yd (91 m).[4]
The Mills bomb was developed into arifle grenade by attaching a metallic rod to its base. This rod-type rifle-grenade had an effective range of about 150 yards (140 m).
The operating procedure was to insert the Mills bomb rod down the barrel of astandard rifle, put a specialblank cartridge (Ballistite cartridge) in the rifle'schamber, place the rifle stock on the ground, then pull the Mills bomb's safety pin, releasing the safety lever and immediately fire the rifle. If the soldier did not launch the grenade quickly, the grenade's fuse would time out and explode.
The British soon developed a simple cradle attached to the rifle'sbayonet lug to hold the safety-lever in place and prevent accidental detonations.[6] However, it was found that the repeated launching of rod-type grenades caused damage to the rifle's barrel, causing the middle to bulge out due to the prolonged pressure spike from driving the much heavier, larger projectile up the barrel (typically a much faster process than with a normal bullet); a rifle cartridge rapidly burns up all the available powder, which fills the volume behind the bullet with extremely high pressure gases (tens of thousands of PSI), the pressure rising as the bullet moves up the barrel, peaking at some point before the bullet leaves the muzzle.
With the much heavier grenade and rod, the cartridge had to accelerate a much heavier mass, which resulted in the powder burning up and the pressure peaking before the rod had got more than a part of the way up the barrel, putting peak pressure on sooner and sustaining it for longer.
The British subsequently developed a cup-type launcher to replace the rod-type rifle-grenade. In this design, a can-shaped launcher was attached to the muzzle of the rifle and a gas check disc was screwed onto the base of the grenade before the grenade was placed in the launcher. The safety pin could then be removed as the launcher cup kept the safety-lever in place.
The operator inserted the ballistite cartridge into the rifle before setting the stock, angled on the ground to absorb the recoil of the weapon. When the cartridge was fired it pushed the grenade out of the cup releasing the lever. The cup-type launcher could launch the grenade about 200 yards (180 m).
Lee–Enfield rifles equipped with the cup launcher were sometimes modified with copper wire wrapped around the stock, to prevent the wood from splitting under the increased recoil.
If necessary, both the rod and the gas check grenade could be thrown as a standard hand-grenade. The cup discharger was typically on issue to the British Home Guard rather than the regular British Army.
The first version.
The explosive was filled through a small circular plug on the upper half, the detonator assembly was inserted into the centre tube through the bottom of the grenade body via the base plug, the striker and spring was held in tension through the middle by the lever that was held down on the lugs (ears) located on the top of the grenade body via a split pin and ring called the safety pin/pull ring.
It was issued in May 1915 and entered general issue when mass production caught up a year later in 1916.
Hand/rifle-grenade version with a rodded base plug drilled with a threaded hole for a launching rod, allowed it to be fired from a rifle.
Modified Mk 1 with a new-style iron base plug that was easier to tighten with the fingers without the need for a spanner.
Fitted with a new-style body with a larger filler hole plug and more solid -lever lugs/ears but retaining the Mk II style plug.
Introduced in May 1918.[7]
It used the No. 23 Mk III body with a new-style plug and a detachable base plate for use with arifle discharger cup.
Mostly made of iron, it was drilled and threaded for attaching a metal disk called a gas check to fire the grenade from a cup discharger (Burns) mounted on a rifle's muzzle and launched using a balastite blank cartridge.
The shellac-coated "Mesopotamian" variant was designed to keep moisture and humidity out of the detonator's fuse.
The No. 36M, was specially designed and waterproofed withshellac for use in the hot climate ofMesopotamia in 1917 at first but remained in production for many years.[8]
The Mills bomb was adopted by theBritish Army as its standard hand grenade in 1915 as the No. 5.[8]
By 1918 the No. 5 and No. 23 had been declared obsolete and the No. 36 (but not the 36M) followed in 1932.
At first the grenade was fitted with a seven-second fuse but in theBattle of France in 1940 this delay proved to be too long, giving defenders time to escape the explosion, or even to throw the grenade back. Therefore, the delay was reduced to four seconds.
The British Army continued to use grenades with a seven-second fuse for use in rifle mounted grenade projectors where the fuse time was required to allow the grenade to reach its full range.[citation needed]
After the Second World War, Britain adopted grenades that contained segmented coiled wire in smooth metal casings.
The No. 36M Mk.I remained the standard grenade of theBritish Armed Forces and was manufactured in the UK until 1972, when it was replaced by theL2 series.[9]
The 36M remained in service in some parts of the world such as India and Pakistan, where it was manufactured until the 2000s.
Mills bombs were still being used in combat as recently as 2004, for example in the incident which killed US MarineJason Dunham and wounded two of his comrades.[10]
The last major operator of the Mills bomb was India who only replaced it in August 2021 with a new Multi-Mode Hand Grenade (MMHG).[11]
{{cite web}}: CS1 maint: numeric names: authors list (link)
