Jump to content


British 75mm HV vs 77-mm


  • This topic is locked This topic is locked
11 replies to this topic

Slash78 #1 Posted Aug 20 2013 - 21:21

    Captain

  • Players
  • 12034 battles
  • 1,613
  • Member since:
    03-17-2013
In game these two guns are very similar, with the 77-mm being slightly better.  145mm vs 148mm Pen.  Should this be the case?

It was my understanding (and correct me if I'm wrong) that the 75-mm HV was originally developed from the projectile used in the 75mm Mk V gun (and US M3) due to the better HE shell available compared to the 17-pdr and the large numbers available from the US.  The reasons it wasn't adopted were two fold.  First, it was still too large to fit in a Cromwell and second, it's performance was weak due to lower then expected penetrating power and a tendency of the AP shells to shatter.  That overall the gun wasn't any better or even worse than the already available US 76mm (128mm Pen in game).  They found this out around Novemeber 1943 and had to start time consuming development some time after that of what became the 77-mm gun.

Now when I first saw these numbers I thought that WG had nerfed the 77-mm down to about what the 75mm HV would have been, but I found at least one set of numbers that backs up the 77-mm (it and the 17-pdr are shown to do roughly their ingame Pen at 500m with ABCBC, though angles aren't given and I don't have access to the resource material).  

The fact that the 75mm HV and 77-mm's numbers are so close give people reason to complain (as if they really need a reason).  Should the numbers be so close?

WeaponsCrate #2 Posted Aug 20 2013 - 21:25

    Major

  • Players
  • 92 battles
  • 13,207
  • Member since:
    03-02-2011
IIRC the 75mm HV developed into the 77mm by the time it entered service to use existing 17-pdr shots (not the propellant casings, though), so it probably makes sense that they're nearly identical.

Edited by WeaponsCrate, Aug 20 2013 - 21:26.


Slash78 #3 Posted Aug 21 2013 - 00:36

    Captain

  • Players
  • 12034 battles
  • 1,613
  • Member since:
    03-17-2013

View PostWeaponsCrate, on Aug 20 2013 - 21:25, said:

IIRC the 75mm HV developed into the 77mm by the time it entered service to use existing 17-pdr shots (not the propellant casings, though), so it probably makes sense that they're nearly identical.

But if they were, then they would have made the 75mm HV instead.  

Again, why did they start with the non-British 75mm to begin with than the British 17-pdr (76mm) projectile and try to fit it on an already 3" (76mm) British casing (which they eventually did with the 77mm)?  Or why not just use the US 76mm?  Because, the 75mm offered a better HE option as well as (in theory) good penetration.  The emphasis of the program was 1) get a higher velocity gun to fit on a Cromwell and 2) for it to have a better HE capability then the 76mm or 17-pdr, which the 75mm Mk V/M3 had.  The gun failed to reach #1.  And the 77-mm failed both #1 because it couldn't fit on the Cromwell, hence the design of the Comet and it failed #2 because it in fact used the same projectile as the 17pdr with it's poor HE option.  And with D-Day coming up they had to take the time to rework the weapon they had been working on (Vickers proposed it in 1942, work started i April of 1943 and by Oct/Nov they decided to rework it into the 77mm, wasting a lot of precious time).  See what I'm getting at?  They obviously couldn't/weren't that similar in performance.

Daigensui #4 Posted Aug 21 2013 - 00:59

    Major

  • Players
  • 31249 battles
  • 29,991
  • [KANCO] KANCO
  • Member since:
    11-09-2012
A topic on that from a while back. The basic conclusion was that the records were not reliable.

Ogopogo #5 Posted Aug 21 2013 - 01:15

    Major

  • Beta Testers
  • 25503 battles
  • 6,997
  • Member since:
    07-15-2010
The 75mm HV and the 77mm are very similar projects, the only difference being the projectile. Both shells used the 3-inch 20 cwt AA gun cartridge, while having different projectiles. The cromwell could not mount the 75mm HV, not because of the size or weight, but because of the internal mantlet. Vickers had designed the 75mm HV for an external mantlet, with the trunnions on the outside, but the cromwell had an internal mantlet in the end, and the displacement towards the rear of the turret, along with a few other things, meant the gun would no longer fit. During the design process for comet, it was decided to change the shell to make use of the same projectile as the 17 pounder. While it did offer worse HE performance, it was eased somewhat by the fact the 77mm shells were easier to handle, and they offered improved armour penetration performance while still managing better HE performance than the 76mm, especially later on when HE shells were loaded to a lower velocity and pressure to allow for thinner walls.

Technically speaking, they should be similar (discounting the quality of the penetrator) with both tanks having a muzzle energy thanks to the same cartridge. Seeing as the shell weight of the 77mm is slightly more, however, it should maintain a slightly higher energy thanks to energy transfer. A heavier shell will almost always have more energy when fired from the same cartridge as a lighter shell.

As for the 75mm shells having a tendency to shatter, perhaps that may have been due to the fact the 75mm projectile was designed with a lower muzzle velocity in mind. Certainly it would play a part.

Slash78 #6 Posted Aug 21 2013 - 02:45

    Captain

  • Players
  • 12034 battles
  • 1,613
  • Member since:
    03-17-2013

View PostDaigensui, on Aug 21 2013 - 00:59, said:

A topic on that from a while back. The basic conclusion was that the records were not reliable.

But it also looks like that Pen should be lower for the 75mm HV.  The biggest complaint about the 77-mm is that it's no real upgrade to the 75mm HV.  If they nerf the 75mm HV to the 128-135mm range then they can complain about the Nerf instead of the "lack of upgrade" the 77mm brings.

Daigensui #7 Posted Aug 21 2013 - 07:46

    Major

  • Players
  • 31249 battles
  • 29,991
  • [KANCO] KANCO
  • Member since:
    11-09-2012
Better alpha and higher rate of fire aren't real upgrades? Whoever thinks so need to have their heads checked.
Of course, I would support a penetration nerf for HV, since it would fit in with what I have been looking into.

Slash78 #8 Posted Aug 21 2013 - 08:25

    Captain

  • Players
  • 12034 battles
  • 1,613
  • Member since:
    03-17-2013

View PostDaigensui, on Aug 21 2013 - 07:46, said:

Better alpha and higher rate of fire aren't real upgrades? Whoever thinks so need to have their heads checked.
Of course, I would support a penetration nerf for HV, since it would fit in with what I have been looking into.

Come on.  Nothing in this game ever has enough Alpha.  It's like Cowbell int hat regards.  Nearly every "buff" thread starts with "I have a fever and the only prescription is more Alpha" followed by a response then the OP said "Come on baby, I gotta have more Alpha!"

Life_In_Black #9 Posted Aug 21 2013 - 08:35

    Major

  • Players
  • 26288 battles
  • 11,490
  • [KGS] KGS
  • Member since:
    10-29-2011

View PostSlash78, on Aug 21 2013 - 08:25, said:

Come on.  Nothing in this game ever has enough Alpha.  It's like Cowbell int hat regards.  Nearly every "buff" thread starts with "I have a fever and the only prescription is more Alpha" followed by a response then the OP said "Come on baby, I gotta have more Alpha!"

On a completely unrelated tangent here, when I saw Blue Öyster Cult back in 2010 they didn't even have a cowbell at all when they played Don't Fear the Reaper.  :angry:

Dirizon #10 Posted Aug 21 2013 - 13:06

    Major

  • Players
  • 27926 battles
  • 5,259
  • Member since:
    06-05-2011
The 7.5cm weapon used on the Valentine (MKV) is the United Kingdom gun resembling the USA M2 / M3 / M6 7.5cm guns featured on M4 Sherman and M24 Chaffee. These weapons are of an older French Gun / Howitzer design, using smaller shell casings and thinner shell walls, and having lower shell velocity. As a result, better HE performance and general purpose performance resulted compared to later war high velocity tank killing 7.5cm weapons. Now the Cromwell and Churchill top gun, the 7.5cm HV - l am not really sure what gun that one is historically. The 7.7cm HV is Comet's historic gun, a cropped version of the 17 PDR to fit inside Comet's turret, having less firing pressure and less powder in the slightly altered 17 PDR case. The changes lessened the effectiveness of the 7.7cm HV a little below that of 17 PDR, though nonetheless still excellent for 1944-45 (performance greater than that of Panther L7O 7.5cm) They named it 7.7cm HV to differentiate the two. I believe the 7.5 HV is simply a schematic or theoretical gun drawn up to be in the game to separate the 6 PDRs from the 7.7cm HV and 17 PDR - the first being to weak for later tier 5, 6, 7 play while the following ones being too strong for tier 5.
lts interesting to note, that despite these changes, the 17 PDR stayed in tier 5 for the French line.....Though radically changed from when it was first introduced (SA 35C stock gun) the French TD kept the gun and has incredible tier 5 TD performance at stock.....When first introduced when the French line arrived, it had the performance of 144 Pen 135 damage, which interestingly is the new 7.5cm HV guns performance....Sort of funny to see how Wargaming works.
0h and...

Quote

.
Daigensui
Today, 08:46 AM
Better alpha and higher rate of fire aren't real upgrades? Whoever thinks so need to have their heads checked
The 7.5cm HV fires the same speed on Cromwell and Comet....both 15.4. Likewise, the upgrade to the 7.7cm HV you still have the same rate of fire, 15.4. In fact, l think that are these guns max rate, 15.4. Hardly a firepower upgrade. The damage from 14O to 135 is negligible. The AP / AP Cored (145/2O2 & 148/2O8) Pen changes are negligible. As l said, hardly any upgrade. 17 PDR, now that is an upgrade. l've painfully went through them, gun to gun....

Anlushac11 #11 Posted Aug 21 2013 - 14:26

    Major

  • Players
  • 37445 battles
  • 2,345
  • Member since:
    05-25-2013
IMHO...

the confusion stems from the fact that the OQF 75mm is not the same as the Vicker 75mm HV.

The OQF 75mm in the Valentine, Churchill, and Cromwell were based off 6lbr bored out to 75mm and breech modified to fire the US 75mm rounds.

The Vickers 75mm L/50 used a 3 inch 20 cwt AA gun shell casing mounted with the US AP projectiles.

The 77mm was based on the Vickers with bore increased from 75mm to 76.2mm and the breech changed so it could use the 17lbr rounds.

AlasdhairM #12 Posted Apr 17 2014 - 18:54

    Corporal

  • Players
  • 579 battles
  • 43
  • Member since:
    07-19-2012

 

The 7.5cm weapon used on the Valentine (MKV) is the United Kingdom gun resembling the USA M2 / M3 / M6 7.5cm guns featured on M4 Sherman and M24 Chaffee. These weapons are of an older French Gun / Howitzer design, using smaller shell casings and thinner shell walls, and having lower shell velocity.

 

 

The gun to which you refer, the Canon de 75 Modele 1897 AKA 75mm gun M1897, was not the basis for the M2/M3/M6 series of 75mm guns. While they shared similar HE shells and cases, the AP and antitank ammunition was of a significantly more modern design, and the guns themselves are of a vastly different design, with a sliding semiautomatic breechblock, as opposed to a screw breech, and having different barrels and rifling. The US did, however, use M1897 75mm guns mounted on halftracks as a field measure for mobile anti-armor support, type classified as the M3 GMC.

 

Also, unrelatedly, why 7.5cm?

 






1 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users