Why was 7.62 a standard caliber during WWII?

[MachIVshooter]

Sweden sent equipment and volunteers to help the Finns.

Ah. I figure the Finns probably used whatever they could get their hands on at a given time, since they never really figured out who they were with or against from one day to the next.

That must have been during a time when they were at odds with both the Russkies and the Germans, and couldn't get Mosins or German Mausers.

 

[Cosmoline]

The standard caliber for shoulder weapons ranged from 6.5 to 8mm from the 1890's through WWII. The reason for this was primarily the advent of smokeless powder. This higher pressure propellant could send smaller rounds at much higher velocities than black powder. By using smaller rounds, the armies could save money and the troops could have more ammo with less weight.

By WWII the powers had settled on spitzer-loaded cartridges with a bullet diameter of between 7.7mm and 8mm. The smaller 6.5's had mostly been dropped or were being phased out due to perceived inferior performance.

Another factor was the lack of cavalry, so you no longer needed a round massive enough to drop a charging horse.

You always have military forces copying each other, which is why you have similar diameter ball ammo. At the same time, they don't want to have ammo that can be used by the enemy. Finland is a rare example of a nation using the ammunition of its major foe. But it's a bold tactic, and can backfire (literally) very easily.

So you get all kinds of minor variations within the same general parameters. Even back to the Brown Bess' 11 bore slug, which was a notch larger than the French balls. So some French soldier picks up the ammo of an English soldier and it won't fit in his .690" Charleville

 

[Deanimator]

That must have been during a time when they were at odds with both the Russkies and the Germans, and couldn't get Mosins or German Mausers.

It was at the time (and possibly later) of the Soviet invasion of Finland.

No matter what, the Finns were against the Soviets, until almost the end of the war when they concluded their separate peace.

The Finns also used Italian Mannlicher-Carcanos.

 

[Deanimator]

The standard caliber for shoulder weapons ranged from 6.5 to 8mm from the 1890's through WWII.

Don't forget the 6mm Lee used by the USN and USMC before they adopted the '03 Springfield. It was used both in the Lee straight pull rifle and in the Browning "potato digger" machine gun.

 

[FenderTK421]

I think the point Bwana was trying to make, w /out every one over-thinking it, was that battlefield conclusions had led to the general trend of countries repeatedly adopting smaller/faster cartridges over a course of some 200 years... some great info in this thread though.

 

[akodo]

Brits and USA used 30 caliber, but they were actually slightly different (308 vs 311)
Russia used 30 caliber 311
Germans used 8mm
French used 8mm and 7.5mm
Canada used 7mm some, but also used the same rounds as the brits.
Italy used 6.5mm and 7.3mm
Sweden, Norway and other Nordic nations, when not using captured Russian rifles used 6.5mm
Switzerland used 7.5mm
Japan used 6.5 and 7.7mm


this makes me reject your basic premise that the 30 was a standard caliber.

Second, you cite rifles and machineguns as both using 30 cal...well, whatever the rifle cartridge of a nation was, that's what they'd use in their machineguns! It is true the Russians had 30 caliber pistols and SMGs, but this was just logistics, no need for separate bullet factories. I suspect this is the same with the M1 carbine being 30 caliber.

All these nations used calibers between 6.5 and 8mm because they all moved to smokeless powder which burned faster and allowed for a smaller high velocity cartridge. 9mm was too big and wasteful of space, started out too slow, etc etc, and 5.5 mm was too small and wasteful of powder, powders of the day didn't burn fast enough to really take advantage of such a light round, etc etc.

 

[Zoogster]

I have never seen that rifle before, was it full auto?

Of course, the whole purpose of an assault rifle was to fill the roles of submachineguns, but give them greater power and range. The role of submachineguns at the time of ww2 was primarily in storming and assaulting positions where close range engagements were expected. Like urban combat.
Firing full auto at targets at relatively close range.
Tactics developed in WW1 were similar and the likely origin of later tactics. The whole "walking fire" while advancing and taking trenches. Full auto fire intended to be "walked" into the enemy while advancing.

So "assault rifle" calibers were adopted, which gave up the power and range of a typical battle rifle, but were more controllable while fired in full auto.
If never intended to be fired in the full auto role they would have stuck with the more powerful calibers of typical battle rifles.
A semi-auto "assault rifle" would have seemed pointless and actually worse than a semi-auto battle rifle to them at the time. Like going backwards.

The ONLY reason the US went to 5.56 was that it was somewhat controllable in full auto fire

Exactly. They chose a round that was less powerful but was controllable in full auto fire.
They do not use them in the original intended role today.
Full auto fire was intended to be the standard mode of operation, and as a result a less powerful caliber that allowed a higher rate of accurate fire was adopted.
They have since retained the rifle (with updates) and cartridge for other reasons unrelated to the original reasons for adoption.

At the time if they had intended for soldiers to operate in semi-auto fire most of the time they would not have gone down to a fast .22 caliber weapon.


Compare that to the PDW type weapons they have come up with more recently. Similar concept. Even less powerful low recoiling rounds that give up stopping power per round but are designed to compensate with a very high rate of fire. (Which have since proven unpopular as obviously the 5.56 rifles already used accomplish almost the same thing with even greater power per round, and require no new purchases, or additional logistical concerns.)

 

[anhedonic]

I'm not sure we will ever see a standard military caliber much under 0.25" regardless of powder improvements due to the capillary action of such a small bore. It becomes increasingly difficult to insure that a wet barrel doesn't harbor a "liquid obstruction"...

 

[Bwana John]

I'm not sure we will ever see a standard military caliber much under 0.25"

***?

 

[MarCn]

The name of the game to the military is lethality - how good is a rifle for killing? The answer, except when explosive projectiles are involved, is in momentum of the projectile, which is bullet mass times bullet velocity.

With early black powder, there was not enough pressure generated to get high velocity, so the choice was to use a heavy (thus large diameter) bullet. Bullet diameters of 3/4 inch (e.g., the Brown Bess) were common.

As powders improved, higher velocity could be achieved and lighter bullets became as lethal as the earlier big bullets. By the U.S. (un)Civil War, the standard caliber was .58 or thereabouts. This shortly went down how adipex works to about .45 caliber or its metric equivalent of about 11mm. Around 1900, smokeless how to store viagra powder, with its higher pressure, allowed for bullets as small as 6mm/.24 caliber to be considered lethal enough if high enough velocity could be achieved.

Many armed forces, including the U.S. Navy, purchased 6mm and 6.5mm rifles, mostly because of weight savings and in many cases because their soldiers were of small stature. But those cartridges were not able to gain enough velocity with the powders of the day to achieve the desired lethality, and most of the armies that had gone to 6.5 and smaller went back up the scale, or tried to, to a bullet of around .30/8mm.

That turned out to be close to the ideal. Adequate velocity and bullet weight for good lethality and the penetration of defenses like logs and of that new invention, the automobile.

Arising out of the last days of WWII, there then came a demand for faster firing weapons, selective fire rifles which were given the collective name "assault rifles" (from the German "Sturmgewehr"). But these presented a problem when full power ammunition (as then understood) was tried. The recoil was excessive and the rifles were simply uncontrollable in full auto fire.

Given the alternative of being restricted to semi-automatic fire or again reducing the rifle caliber or power, armies chose the latter approach. Today, most military rifles are chambered for one of two medium power cartridges, the 7.62x39 or the 5.56 NATO. But the same problem faced by (among others) the Japanese and the Italians, once again rears its head. The light, low recoil cartridge, mainly the 5.56, has proven lethal enough as a pure anti-personnel weapon, but its light bullet fails in penetration of defenses. So, back to the future with something like the 6.8? Who knows, but it all sounds familiar somehow.

Jim

Good point

 

[Mandolin]

smokeless how to store viagra powder,

Huh? Is that what he meant to say?

 

[stevekl]

Yeah you know, sometimes I wonder about calibers.

Just recently I saw something interesting. It was on a website about cartridge collecting and I saw some examples of some artillery shells used in Hotchkiss guns of the late 1860's/1870's. And they were sized like 37mm, 47mm and 53mm

When I read that, I thought, hold on, those are the same calibers used by tank and anti-tank guns during World War 2. The Germans and Americans used 37mm guns. The French had a 47mm gun. The British had a 53mm gun (their Six Pounder).

So why are militaries of the 1940's using the same sized shells as they did in the 1870's?

If I had to guess, it's because it's cheaper and easier to just use the same tools and dies over and over again. Rather than re-invent the wheel.

I think at some point in history someone invented the .30-30 (that's the earliest .30 caliber cartridge I can think of) and used a .30/7.62mm bullet just as an arbitrary choice. And they just kept using that size because the tools and dies needed to make a .30 caliber hole for swaging or casting already existed.

I wonder about the guy who invented the .22. Why not .20? Why not .25?