Question Weapons sizes

chris h · #1 September 7th, 2015, 04:30 AM

Does anyone know why some weapons have odd sizes although perhaps odd is not correct word?

For instance the German 88mm. Why not 90mm or 85mm? Another example would be the 81mm mtr or the 7.92mm mg.

scorpio_rocks · #2 September 7th, 2015, 07:25 AM

Quick answer - No reason at all!

The gunsmith designed the gun with what ever caliber he desired!

Some are the result of "conversions" from inches to mm (ie 12.5 or 12.7mm = .50 inch)

Also it depends often on what is being measured - sometimes it is bullet diameter, case diameter, bore diameter (with or without including rifleing), etc.

Often if a particular caliber round is available in large quantities you will design your weapon to match, perpetuating the number.

Often different manufaturers will measure/describe different things to mean the same size - look at the .38 special, it fires same size ammo as a .357.

Suhiir · #3 September 7th, 2015, 11:36 PM

Ammunition is a trade off between diameter/mass, powder charge/velocity, and if it has a warhead bursting charge.

Take the classic American .45 caliber M1911, big low velocity bullet and limited magazine capacity because of this. This is why many armies use 9mm handguns. Smaller higher velocity bullet and a much larger magazine capacity. Which is "better"? That's an argument that will never be resolved because it's more subjective then objective.

"Odd" calibers are because of this. You trade off caliber for mass, ammo capacity, and often velocity. Sure they make big high velocity ammo, but due to it's size it's HEAVY. This is why naval guns are generally larger then land based systems. You have a whole ship to store ammo and ammo handling equipment in.

RetLT · #4 September 10th, 2015, 10:10 PM

And what is with the British and their 6lb, 17lb, and 25lb guns?

How does the weight of the shell correspond to the diameter of the barrel and why on earth would anyone use such a system?

scorpio_rocks · #5 September 11th, 2015, 05:26 AM

Quote:

Originally Posted by RetLT

And what is with the British and their 6lb, 17lb, and 25lb guns?

How does the weight of the shell correspond to the diameter of the barrel and why on earth would anyone use such a system?

It goes back to a time of cannonballs where a gun was rated and sized by what weight of shot it fired. (A similar reason spawned the "gauge" system for shotguns - ie 12 gauge fires a single ball 1/12 of a pound). With standardised composition of cannon shot it worked - everyone knew what was being measured, rather than "which diameter exactly?".

The system stayed even when cannon balls were no longer used giving us the WWII era 2 pounder (40mm), 3 pounder (47mm), 6pounder (57mm), 17pounder (76.2mm) and 25pounder (87.6mm) amongst others.

Griefbringer · #6 September 11th, 2015, 12:45 PM

And measuring cannons by the weight of their ammo dates back at least to the 16th century. At a time when cannons fired spherical projectiles, there was a direct correlation between the diameter and weight of the projectile (cast from metal of a given density).

As for WWII era, British were not happy to designate all of their artillery pieces by the weight of the shot, so some of them were designated by the barrel diameter.

troopie · #7 September 11th, 2015, 10:32 PM

Quote:

Originally Posted by Suhiir

Ammunition is a trade off between diameter/mass, powder charge/velocity, and if it has a warhead bursting charge.

Take the classic American .45 caliber M1911, big low velocity bullet and limited magazine capacity because of this. This is why many armies use 9mm handguns. Smaller higher velocity bullet and a much larger magazine capacity. Which is "better"? That's an argument that will never be resolved because it's more subjective then objective.

"Odd" calibers are because of this. You trade off caliber for mass, ammo capacity, and often velocity. Sure they make big high velocity ammo, but due to it's size it's HEAVY. This is why naval guns are generally larger then land based systems. You have a whole ship to store ammo and ammo handling equipment in.

I've always heard that the M1911 was designed to be a stopper. The pistols used by the US Army would not stop a Moro crazed on dagga and the M1911 was designed to do that. When it came into service the Moro uprising was long over, but that's an army for you.

troopie

Suhiir · #8 September 12th, 2015, 07:48 AM

Quote:

Originally Posted by troopie

I've always heard that the M1911 was designed to be a stopper. The pistols used by the US Army would not stop a Moro crazed on dagga and the M1911 was designed to do that. When it came into service the Moro uprising was long over, but that's an army for you.

troopie

Personally I've always MUCH preferred the .45

DRG · #9 September 12th, 2015, 07:57 AM

Quote:

Originally Posted by Suhiir

Quote:

Originally Posted by troopie

I've always heard that the M1911 was designed to be a stopper. The pistols used by the US Army would not stop a Moro crazed on dagga and the M1911 was designed to do that. When it came into service the Moro uprising was long over, but that's an army for you.

troopie

Personally I've always MUCH preferred the .45

I agree, mines aproaching it's 100th bithday......

RetLT · #10 September 12th, 2015, 11:40 AM

A lot comes down to shot placement. A .22 to the right spot is more effective than a .45 to an extremity.

I carried a .40 cal Glock on duty and a .380 Walther off duty.

The .40 cal had plenty of stopping power and ammo. The Walther had less of both but was easy to conceal. I figured that I am not going to get into an extended firefight off duty and that if I shoot a guy 7 times center mass with hollow points and he does not go down I should just give him my wallet an car keys and apologize.