USA: Early M4 hulls with L40 gun?
 

There does not seem to be any unit to cover the early M4 (welded hull) equipped with the L40 gun. As far as I can tell, all early M4's seem to be equipped with the L37 gun. The only M4 variants in game available in 1942 with the L40 gun seem to be the M4A1's, with the cast hull.

Is this intentional?

Re: USA: Early M4 hulls with L40 gun?
 

The penetration of both guns are the same, with the only real difference being one point in accuracy, so the things are basically identical.

I vaguely recall a massive data check on the varicose Sherman variants being done a decade or so back in the MSDOS days. Up until then, I had just thought that a 75mm Sherman was just a 75mm Sherman.. :)

Since nobody has brought this point up since then, if it is a valid point, then I suppose that everyone is happy with the existing Sherman models?

(Me, I just find the one with the best frontal armour as a general rule and buy that).

Re: USA: Early M4 hulls with L40 gun?
 

Want that extra point of accuracy dangit! Heh.

Looks like The M4A3E2 (76) #022 and #186 are duplicates, so maybe one of those can become the M4 L40?

Re: USA: Early M4 hulls with L40 gun?
 

So which M4(mouthful) do you actually want then, what start date, and as I would not know a "cast hull" from a "welded hull" if it bit me, what armour scheme?. Is it just a copy and paste of an existing M4(mumble) with a new gun and name? - if so, just say "Copy unit #xx, give it the L40 gun and the jumble of letters and digits becomes M4Abc123"...

(I can see why we Brits renamed US things with real names in WW2, not some M-number and a jumble of letters and digits.. ;) Which M3, did sir mean - the light tank M3, half track M3, the medium tank M3, the M3 SMG, the Tractor Crane (2 ton) M3. Much easier to use proper names for things! :D)

Re: USA: Early M4 hulls with L40 gun?
 

Yes, they are,.......... will investigate.................

edit.........

HA!.......it's been that way for over 12 years and if anyone noticed before this they kept it to themselves

Re: USA: Early M4 hulls with L40 gun?
 

Well... the idea was to copy unit #302/303 to give them the L40 (Weapon 47).

But...

Now that I'm looking into this some more, I'm kind of doubting whether there actually was a distinct L37 version of the M4's gun at all. The only reference I can find that mentions both the L37 and L/40 is in wikipedia:

https://en.wikipedia.org/wiki/75_mm_Gun_M2/M3/M6

Which says: "Barrel length: 40(37.5) calibres (3 m)". The same page also refers to it as the "75mm/L40." I can't find any document that actually refers to the 75mm/L40 and 75mm/L37 (or 37.5) as distinct weapons. One might refer to the "75mm M3" (gun, not tank) as either the L37 or L40, but never refer to each as distinct weapons.

It looks like it might just be that some documents rounded up. In which case, the fix would be to replace all weapon #45's with weapon #47.

But I would like for someone who knows Shermans better than I to confirm...

Re: USA: Early M4 hulls with L40 gun?
 

Don't forget the M3 howitzer (not to be confused with M3 gun).

Re: USA: Early M4 hulls with L40 gun?
 

Heh. Yeah, it's pretty crazy.

"Is there some reason a robot made of wax can't take a nap standing up in the middle of a bunch of wax robots? Or does that confuse you?"

https://www.youtube.com/watch?v=MkJDuLbR170

Re: USA: Early M4 hulls with L40 gun?
 

And how about M3 Scout car? ;)

Re: USA: Early M4 hulls with L40 gun?
 

I'm no expert, but I can tell you that British and US barrel lengths were measured from the mouth of the chamber to the barrel end (bore length), but continental nations, including the USSR, measured from the rear face of the breech, giving a longer measured length.

Therefore, the British and US would call it a L40, but if the Soviets bothered to do their own measurements they'd call it a L46, or there abouts.

Because of this, US and Brit guns get the 'short end of the stick' in almost all games that use barrel length calculations.


As for hulls.

I think there were 6 hull types:

• Early Cast dry tiny hatches
• Late Cast wet large hatches
• Early Welded dry small hatches
• Late Welded wet large hatches
• Composite welded
• HVSS Wider with wider tracks

3 nose types:

• Three piece bolted flanges
• Soft nose casting - rolls under smoothly
• Sharp wedge shaped front

3 Turret Types:

• Single hatch early short 75mm One hatch 2 lids
• Two hatch later 75 or 105mm 1 large 1 small hatch
• T23 last long 76mm 2 hatches large

British to US conversion:

• Sherman I = M4
• Sherman II = M4A1
• Sherman III = M4A2
• Sherman IV = M4A3
• Sherman V = M4A4
• Sherman IIAY + HVSS

Gun types/naming conventions:

No notation = 75mm
A = 76mm
B = 105mm
C = 17pdr
and so on so an Sherman IIIC was a M4A2 w/ 17 pound gun.

W = wet storage
E8 = (76)W HVSS
Jumbo = Thicker armour




Cross

Re: USA: Early M4 hulls with L40 gun?
 

the M4A3E2 Assault Tank had Grousers fitted to the tracks. Don't forget about Grousers. Other than the US, the Free French units received one M4A3E2.
I am psychologically crushed beyond relief that Grousers and the lone Free French tank are being shunned by the war gaming community.
Where's the love?

Re: USA: Early M4 hulls with L40 gun?
 

There were some welded (M4A2) and cast (M4A1) hulls with dry stowage and large hatches (in the M4A2's), if these sources are accurate:

http://afvdb.50megs.com/usa/m4sherman.html#M4A2

---

http://the.shadock.free.fr/sherman_m...gehatches.html

Granted, that's not very many. And the M4A2's were mostly (exclusively?) USMC. And the 105mm armed versions had a stowage that was not wet, but offered other modifications that achieved the same effect, if I'm understanding it correctly.

---

All of this looks to be pretty well represented in the game, by the way. Large hatches improved crew survivability by allowing for better escapes, I assume. And wet stowage greatly decreased ammunition fires (although it had little to do with wetness). From what I can tell:

Survivability 2 = Dry stowage small hatch.
Survivability 3 = Dry stowage large hatch.
Survivability 4 = Wet stowage large hatch.

Additionally, the frontal armor values:

Cast small hatch: 51mm @ 55 deg.
Cast large hatch: 64mm @ 47 deg.

Welded small hatch: 51mm @ 56 deg.
Welded large hatch: 64mm @ 47 deg.

I'm led to believe that the cast hulls offered less protection than the welded ones for the same armor values, though.

(All HVSS hulls had the large hatches, I think, except for a few post-war modified tanks. I'm not sure where the composites fit into this.)

Re: USA: Early M4 hulls with L40 gun?
 

Oh, but back to the actual question of the thread:

Cross, do you think you can confirm that there was only one actual version of the 75mm M3 gun, and that the alleged two lengths were just rounding or different measuring?

Re: USA: Early M4 hulls with L40 gun?
 

I can tell you that a primary US document lists the gun length as 118.36 inches, which is 3007mm or L40.

I don't know how they measured, but there's no muzzle brake to muddy the waters, and if they included the breech, as they do on the continent, then the breech would have to be about 20cm to explain a L37 or L37.5 length.


https://dl.dropboxusercontent.com/u/...es/75mm-M3.gif


cross

Re: USA: Early M4 hulls with L40 gun?
 

According to FM 23-95 75-MM TANK GUN M2 (MOUNTED IN MEDIUM TANK M3)
May 4, 1942, the gun was measured "Length (muzzle to rear face of breech ring)". I would imagine it would be the same for the 75-MM Tank gun mounted in Medium Tank M4.

Re: USA: Early M4 hulls with L40 gun?
 

It's my understanding that the rear of the breech is farthest from the loader and where the bore begins. This would appear to confirm that the L40 does refer to a bore length of 3007mm.

Cross

Re: USA: Early M4 hulls with L40 gun?
 

It's my understanding that the rear of the breech is farthest from the loader and where the bore begins. This would appear to confirm that the L40 does refer to a bore length of 3007mm.

Cross

Re: USA: Early M4 hulls with L40 gun?
 

So it sounds like, unless anyone has any information to the contrary, there did not exist two distinct 75mm guns for the Medium Tank M4. 75mm/L37 and 75mm/L40 were simply two different ways of measuring the same gun.

In that case, Mobhack, the fix would be to simply replace all L37 guns (#45) with the L40 (#47).

Re: USA: Early M4 hulls with L40 gun?
 

I've contradicted myself...
If the continental armies also measured from the "rear face of the breech" then the USSR and Germany also used a bore length to determine the L** calibers, and my original source is wrong.

Don't you love rivet counting :D


Cross

Re: USA: Early M4 hulls with L40 gun?
 

From reading the manual, and looking at the diagrams it seems that only the threaded front part of the breech where the barrel screws into would be in the measurement.
3. DESCRIPTION OP GROUPS.—a. Gun group.—(1) Tube.— The tube (fig. 1) is formed of one piece of alloy steel. The rear end of the bore is suitably tapered to form the chamber, and from chamber to muzzle the bore is rifled with a uni form right hand twist of one turn per 25.59 calibers. The exterior of the breech end is threaded to screw into the 75-MM TANK GUN M2 breech ring, and the shoulder immediately forward of the threads contains a keyseat for the breech ring key. Forward from the breech ring the exterior is cylindrical and smoothly finished for bearing in the mount for approximately half the length of the tube. The breech face of the tube is re cessed on each side of the bore to form extractor camming surfaces (fig 3).

https://www.ibiblio.org/hyperwar/USA...Fs/FM23-95.pdf

if you want to see the diagrams.

Re: USA: Early M4 hulls with L40 gun?
 

I'm looking into it so we can all stop talking about it.......I'm just not in any kind of hurry....12 years ago all the "regular" Shermans were weapon 47 ( L40 ). sometime between then and 2009 that changed on some models........don't know why but sometime between now and March 2017 I will sit down and figure out when and why it was changed

Don

Re: USA: Early M4 hulls with L40 gun?
 

Oh, we'll always find something to talk about, It seems many of us have a lot of time on our hands. Speaking of which, why aren't you in a hurry? What are you up to? Inquiring idiots have nothing better to do.

Re: USA: Early M4 hulls with L40 gun?
 

According to R.P. Hunnicutt's SHERMAN, the two 75mm guns installed on the M4 Medium Tanks were:

75mm M2 gun, which had the following measurements:

Length of Bore: 28.5 caliber
Length, Muzzle to rear face of breech: 31.1 caliber

and was installed in the T6 Prototype, and the first couple of Shermans off the production line. These are identifiable via the concentric counterweights installed on the end of the barrel; this is due to the gun mount being designed for the longer M3 gun, so the counterweights were a 'hackjob' to make the shorter M2 gun work in a mount designed for the longer M3.

75mm M3 gun, which had the following measurements:

Length of Bore: 37.5 caliber
Length, Muzzle to rear face of breech: 40.1 caliber

and was installed on the massively overwhelming majority of 75mm Shermans (99.99999%) built.

NOTE: The U.S. measured “calibre” as the length from the muzzle to the rear of the barrel (bore), while the Germans measured it from the muzzle to the rear of the breech. Thus, the US 75mm M3 gun would have a calibre of L37.5 under the US system and L40.1 under the German system.

This may be the cause of confusion; someone saw two differing sources, one measuring calibre via the German system (L40.1) and another via the US system (L37.5) and thought there were two 75mm guns with different calibre lengths in Shermans.

Re: USA: Early M4 hulls with L40 gun?
 

Mark,

Does this mean the rear of the breech is in fact closest to the loader and not furthest from the loader?

I'm wondering if the US and British measured calibers by bore length, and the continental armies measured from muzzle to rear of breech, but this amounts to the same thing...

If the US Army used bore length, why does a primary US Army document refer to the 75mm M3 as L40?

If the bore was L37.5 it would be 281cm and if the rear of the breech (providing this is closest to loader) was L40 then this gives a breech length of 19cm. Can anyone confirm that this is a realistic breech length for a 75mm round?

Finally, if Hunnicutt is right that the 75mm M3 was in fact L37.5 and by German/continental measurements it was L40, then it should be left as L40 in the game because all the German L37 guns are given L40 in the game.



Cross

Re: USA: Early M4 hulls with L40 gun?
 

The breech is on the rear end of the cannon. Its front and rear are the same as for a cannon, generally, I would have thought.

These definitions from a 1922 Gunner's instruction manual seem to support my thinking on the matter:

https://books.google.com/books?id=Ss...page&q&f=false

See especially:
Bore
Breech
Breech, face of
Breech Reinforce

Re: USA: Early M4 hulls with L40 gun?
 

Pretty much.

Which document? If you're referring to this one:

https://dl.dropboxusercontent.com/u/...es/75mm-M3.gif

It's referring to the overall length of the gun, which would be very close to the length from the muzzle to breech face.

Re: USA: Early M4 hulls with L40 gun?
 

This might help (from Hunnicutt):

http://iloapp.panser.dk/data/_galler...00_resized.jpg

The difference between L/37 and L/40 is the difference between measurements C and E.

E = C+D

Re: USA: Early M4 hulls with L40 gun?
 

:)Hi Claus. Good to "see" you