Question: Why does the M1 Abrams have two 7.62mm machine guns and one 50 cal instead of three 50s?
Answer: This was explained to me by an Army National Guard Armor officer: it’s the direct result of lessons learned in the Korean War.
When the Abrams was, it was initially planned to have 2 M2 .50 cal machine guns and one 7.62mm. However, at the time in the late 1960s and early 1970s, the senior tankers on the development committee remembered all too well the horrors of trying in vain to fight off the seemingly endless human waves of North Korean and Chinese infantry during the , running out of ammo and being overrun. So they demanded that the planned .50 caliber coaxial machine gun be replaced with a 7.62mm for use against infantry.
What’s the problem with anagainst infantry? Nothing, as long as you don’t run out of ammo. And there’s the rub; the 7.62mm machine gun rounds are much smaller and you can therefore carry a helluva lot more of them, and fire your gun for a lot longer without having to reload. The rate of fire is also considerably higher on the smaller caliber gun. It’s just an all-around better option against soft targets in the open; a “people-pleaser,” as my tanker buddy likes to call it.
The M2 is designed and best suited for use against equipment (but is not, as a persistent myth suggests, a violation of international law to use it against personnel;), and at longer ranges. It’s a good thing to have on hand for augmenting the main gun, but putting more than two on a tank was never even considered, and the initial plan of two was vetoed by the committee over 40 years ago and never reconsidered. The main gun is, for most applications, more than capable of neutralizing hard targets.
Edit: I shared this with my friend who had this to add:
Worth noting why the Pentagon wanted the .50 coax[ially mounted machine gun]: more “stored kills” for light armored vehicles, which could be dispatched without expending limited main gun rounds. The [Tank Commander]’s .50 accomplishes this, but until very recently, it was without the stabilization and optics that lend a lot of the lethality. A .50 coax would have benefited from this at the start.
So whatever advantages a second .50 cal might have added way back when the tank was developed have since become obsolete.
It’s a pity that it’s somewhat hard to model ammo size loadout issues like this in Traveller… unless you’re manly enough to go full TNE Fire, Fusion and Steel. My respect if you are!
There may be other ways for game & system designers to get the ammo size/ammo amount trade-off across to the Referees and the Players. It has the potential to pose really interesting questions and dilemmas, to both weapon builders and actual troopers in the field!
And in the field, aggressive Referees can put in some time pressure, just to kick up the stress level up a few notches…
(And did you catch that bit about the importance of stabilization and optics? That’s nothing but pure late TL 8 to early TL 9 transition, right there!)