The reason behind this change came from the fact that the grooves on the grenade did not work as expected by the inventor.
When thinking about the shape of a grenade, many people will think of the image of the grooves running along the grenade body. Of course those were old grenades and they often had slits along the body. At first glance they look like a pineapple.
Ancient grenades often had slits along the body.
But in contrast to current grenades, they no longer have grooves, but instead have a smooth design. Why is there such a difference and what does the groove on the grenade actually do?
Interestingly, old grenades didn’t actually have these grooves. Grooves only appear after one improvement during combat. Early soldiers made grenades from various items such as a can and gunpowder. However, in 1915, William Mills, a British engineer and inventor, invented a new safer grenade with a manual detonator.
According to Technology, the use of this grenade is quite simple. You just need to pull the detonator to activate the grenade, then throw it at the enemy to have the impact of the explosion and the metal shards to deal damage to the enemy. But contrary to that principle, grenades at that time were not the most lethal weapon. Because it is quite small and difficult to contain enough explosives that can increase the damage range.
Contradictions arose when soldiers needed grenades small and light enough to be carried in battle. That also means, a small grenade can hardly destroy a large number of enemy health if only with the default amount of explosives.
Mills devised a way to cut grooves so that the grenade shell could easily separate into sharp metal pieces.
The solution offered at this point is to create another layer of attack for the grenade. Specifically, making metal shards fly like bullets and damaging enemies immediately after the grenade explodes. Of course there are ways like mixing sharp metal objects inside grenades but Mills decided to use the body of a grenade as an offensive weapon.
That’s why Mills devised a way to cut out the grooves so that the grenade shell could easily split into unpredictable sharp metal pieces.
In 1918, the American Mk2 grenade appeared on the battlefield and it also had a rather deep groove, dividing the surface of the grenade into many squares. Many other countries later adopted this design solution.
But just a few decades later, people created a grenade with a smooth body? Why such a change?
The answer turned out to be very simple. Just because those grooves don’t really work as expected. Mills noticed that the grenades exploded and shattered into pieces at random locations instead of exploding into square pieces.
The reason is that the cast iron layer that makes up the grenade is quite brittle. When detonated, they almost become iron powder under the pressure of the explosion and are not enough to deal damage to the enemy. Only about a third of the grenade body can become shrapnel and cause danger.
Some grenades such as the M26, M33 and M67 all have completely smooth surfaces.
Despite this, slotted grenades are still quite popular in some countries today. These grooves have also been improved to become neater and have better grip. There has even been an improved groove inside the grenade, making it easier for more debris to be thrown.
Some grenades such as the M26, M33 and M67 all have completely smooth surfaces. In addition, they are also significantly lighter than slotted grenades. Specifically, the new generation M67 (duck-billed grenade) grenade is about 200 grams lighter than the old MK2 but has a damage radius of up to 15m.
Thus, it can be understood that the improvement from the trench grenade type to the one with a smooth body is perfectly suitable for combat requirements that require compactness but can still promote the best damage effect.