"Why is a 17lb'er 77mm" Topic

My son asked the caliber of a 17 lb'er. I said 77mm.

However he checked Wiki, and it's listed as 76.2mm (3 inch) – OTHER SITES AGREE, even those referring to it as a 77mm.

So why 77mm?

The shells were a different length from the standard 76mm shells, so they wanted to give it a name that would easily differentiate it logistically.

Never heard it referred to as 77mm before. I've always understood it to be 76.2mm

the 77mm name was given to the comet's shortened 17pdr gun
it is 76. something mm

The 17pdr was 76.2mm – it was never referred to as 77mm.

When they developed a slightly lower-power 76.2mm gun for the Comet, they wanted to avoid the logistic confusion that had plagued the users of 75mm guns, so they called it the '77mm' gun, even though it was actually 76.2mm. Thus ammunition would not be confused with 17pdr or US 76mm ammunition.

Yes, they called it a '77' to avoid confusion with other similar calibres.

Less confused now??

Thought so ;)

And Mr Pickey says….it is 17pdr, not 17lb'er

Mr. Pickey is of course correct. It is a 17pdr.

And it is not, nor was it ever, 77mm.

It was 76.2mm

And the 77mm gun was NOT a lower-powered 17pdr. The 77mm gun was not developed from the 17pdr, and had no relationship to the 17pdr beyond the bore, which was 76.2mm.

But it was called the 77mm gun to avoid confusion with the 17pdr or the US 76mm (which was NEVER called 76.2mm, and called the 76mm to avoid confusion with the US 3-inch gun, which had the same bore but fired different ammunition).

See how easy that is?

-Mark
(aka: Mk 1)

And, to be absolutely clear, with all due respect, the correct spelling is:

MR PICKY

There you are, all clear now!!

mark1 are you sure?
the comet gun was developed from the 17pdr and even fired the same ammo

OK as stated above the 17pdr was 76.2mm and I have never heard of it being referred to as a 77mm sorry. The only gun I have ever heard being called a 77mm was the weapon fitted to the Comet.

Shaun Mark is correct, the story that the 77mm was a "low power" version of the 17pdr is a popular misconception. The 77mm used shorter more compact round than the 17pder based on a 3 inch AA casing and the rounds were not interchangeable, hence the different designation.

Fatman

From Wiki…

The British started work on developing a gun that was small enough to fit on their tank designs – particularly the Cromwell cruiser tank then at the design stage – firing the US 75 mm projectiles (AP shot and HE) but at higher velocity. This 50 calibre long gun, firing a 75mm projectile attached to a necked down 3-inch (76.2 mm) 20 cwt AA gun cartridge through a modified breech, known as the Vickers HV 75 mm, used a larger propellant charge in a larger cartridge. Although the 75 mm HV was a promising weapon, it proved to be too big for the Cromwell tank, which was fitted with the normal QF 75 mm gun in use on other British tanks. When the Cromwell's replacement – the Comet – was at the design stage, the 75 mm HV concept was reworked to fire the same projectiles as the 17-pounder through a shortened 17-pounder barrel, but retaining the 3-inch cartridge case firing from a standard 3-inch breech.[5]

This has the benefit of greater ease of use on tanks, many of which would not have sufficient turret space to accommodate the breech length and recoil distance of the 17-pounder. This new gun's ammunition was not interchangeable with the 17-pounder, however, and to prevent confusion over ammunition supplies, it was renamed the "77 mm HV"—the 'HV' standing for High Velocity—although it was the same 76.2 mm calibre as the 17-pounder. This gun was used in the Comet tank.

Yes, the '77mm' was a re-engineered version of the 75mm High Velocity Gun. It was essentially re-bored to fire the 76.2mm projectiles of the 17pdr.

The only reason why the British Army is last on my list of major WW2 combatants to build in miniature is because I don't understand the artillery naming system.

I've seen it called the 77mm as well.

Imagine the problems of the Soviets when asking for 7.62 ammo.

7.62x25mm?
7.62x39mm?
7.62x54R?

Imagine the problems of the Soviets when asking for 7.62 ammo.

7.62x25mm?
7.62x39mm?
7.62x54R?

I suspect it was only a difference between "pistol" (25) and "rifle" (54) ammo, as the 7.62x39 did not into use until after the war.

"And, to be absolutely clear, with all due respect, the correct spelling is:

MR PICKY"

You are quite right, I thought it looked odd when I typed but I really couldn't be bothered ot change.

Fascinating about the 77mm gun, I never knew it wasn't a cut down 17pdr. Perhaps the Matchbox Comet is to blame in some way?

Mako,

Seen what called the '77mm'?

If you've seen the 17pdr called '77mm' it's wrong (see above).

Martin,

The gunbarrel was indeed a cut-down 17pdr barrel. However, the breech and working parts were those of the HV 75mm.

Tim, not to worry.
Being infantry ammo, that is like a shoebox in the echelon when carrying a tank squadrons worth of ammo and fuel.

Probably smaller than most soldiers porn collections in the eighties at least.

Troop we had a "battle box" for the OC's Porn during exercise.

7.62*38 was Nagant revolver ammo
7.62*25 was TT33 and SMG ammo
7.62*54r was Mosin Nagant and MG ammo

7.62*54r was Mosin Nagant and MG ammo

And that was AFTER rationalization. If the Soviet government had one consistent characteristic, it was that it loved using globally recognized standards. This factor had not been shared by the Imperial Russian government that preceded it.

And so the Mosin Nagant caliber was re-named with the post-revolutionary modernization to become 7.62mm. Originally it was the Imperial Army's "3 line" rifle, a "line" (ли́ния) being a smaller unit of measure than a "dyium" (дюйм) in the Imperial Russian system.

And the sights were originally graduated in "arshins". So antique Mosin rifles (the original M1891, rather than the M91/30) often shoot low … because you may think the site is graduated in meters, but it isn't! And the arshin is rather shorter than a yard, much less a meter.

Remember now, boys, it's 280 "lines" to the "arshin" (= 28 English inches).

And for longer measures it's 16 "vershoks" = 4 "paids" = 1 "arshin" (= 28 English inches).

Just in case you were wondering ….

-Mark
(aka: Mk 1)

And of course, the 3" mortar wasn't 3" either.