Henry Brown wrote:I suggested a single shot grenade launcher like the M-79 earlier in the thread. In real life, it didn't show up until the Korean war era and it saw extensive use in Vietnam as well. But I don't see any technological reason it couldn't be made before that period. It is not a very complicated weapon.
You are right, the M-79 is not a complicated weapon.
BUT, the fuze that it has is non-trivial. It's armed at some distance from the muzzle (30 meters) by centrifugal force generated by the spin of the round. It further will return to safe if it doesn't hit solidly enough to go off. Half of the weight, half of the length of the M-79 grenade is fuze.
The M79 was a result of Project Niblick, an attempt to increase firepower for the infantryman by having an explosive projectile more accurate with further range than rifle grenades, but more portable than a mortar. Project Niblick created the 40 x 46 mm grenade, but was unable to create a satisfactory launcher for it that could fire more than a single shot. One of the launchers at Springfield Armory was the single-shot break-open, shoulder-fired S-3. It was refined into the S-5, which resembled an over-sized shotgun. Unable to develop a suitable multi-shot launcher, the Army adopted the S-5 as the XM79. With a new sight, the XM79 was officially adopted as the M79 on December 15, 1960. (From Wikipedia)
It wasn't a Korean war weapon, but Vietnam.
Machine guns will be first. The Maxim was patented in 1884.
Likewise the explosive used in the shell is a high explosive, and so far the only explosives we know of in the books is black powder and gun cotton. Something on the order of TNT has to be discovered first.
And as several people have pointed out the Hi-Lo pressure system will also take a series of new inventions. The 40 mm grenade development started with an investigation into how much recoil the average soldier could take. This combined with the weight of the projectile gave its speed. Then they had to design something that would chunk it out at that speed, hence the Hi-Lo system.
Back to mistwalker's opening comment in this thread. A lot of armies think the MG42 fires too fast. It has the problem that the enemy soldier gets hit multiple times when once is enough on a round this size. Hence most MG's fire at about 600 rounds per minute.