Home Forums WWII Tank gun loading speeds?

Viewing 5 posts - 1 through 5 (of 5 total)
  • Author
    Posts
  • #40516
    Ivan Sorensen
    Participant

    So this is sort of a peculiar question:

    Does anyone know if there’s an appreciable difference in the loading speed between say the Brit 2 pounder and the short German 50mm gun?
    Or for that matter the German 37mm and 50mm?

    Nordic Weasel Games
    https://www.wargamevault.com/browse/pub/5701/Nordic-Weasel-Games?src=browse5701

    #40537
    John D Salt
    Participant

    I have never come across any authoritative data for this. No doubt it is reasonably correct to say that practically all WW2 tank and anti-tank guns can load a shot every three to five seconds, but that isn’t terribly useful, given that it covers the range of 20 to 12 rounds per minute.

    I doubt that firing speed is critically determined by loading speed; I would expect aiming time to be the dominating factor. Given that effectively all tank and anti-tank guns will have unitary ammunition and quick-firing breeches (with the odd exception such as the ISU-122), I would expect differences in rate of fire to be small. Design factors that might influence things are the traverse and elevation mechanism, the shot sensing policy, and the degree of obscuration.

    Early war British guns (I believe all 2-pdrs and some 6-pdrs) were in free-traverse mountings, where instead of twiddling wheels one simply shoved the weapon with the shoulder (a similar method was used on the 6-pdr; the US 57mm initially added twiddly wheels, then took them off and went back to free traverse). This might make for slightly faster aiming, especially when attempting to fire on the move, which British gunners were trained to do at the start of the war. Among the numerous disadvantages of firing on the move, a reduced rate of fire because of the increased difficulty of loading and aiming is one that is often forgotten.

    By “sensing policy”, I mean whether the gunner is observing the fall of the initial shot and applying corrections. If so, the time of flight will have an influence on rate of fire; distant targets will be shot at slightly more slowly. However British OR-recommended policy for guns known to have quite high ballistic dispersion, such as the 6-pdr and 17-pdr, especially when firing sabot, was to repeat a shot on the same lay in the event of a miss, rather than re-laying. There was also the fact that the high velocity of sabot, and the massive obscuration of the 17-pdr’s muzzle blast, made sensing the fall of shot pretty near impossible anyway. Ultimately this led to “Bovington system” tank gunnery, where shots would be fired very quickly at battlesight ranges of 600 and 1000 yards, relying on the flatness of the sabot’s trajectory to iron out errors in elevation and rangefinding. I think it was Kenneth Macksey who reported a Centurion gunner complaining “‘E wants this f***ing gun to fire like a machine gun”, easier to do with 6-pdr rounds than 20-pdr.

    Obscuration could be a real limit to rate of fire, and I think it is one of Steve Zaloga’s books on the Sherman that reports 76mm Shermans sometimes being controlled down to four rounds a minute because of the time required for dust clouds to disperse. A good anti-tank detachment will wet the ground in front of their position to lay the dust in order to avoid this. After WW2 some experiments were done with a device called a “hoonoo” attached to the muzzle of a 20-pdr and intended to reduce obscuation by deflecting muzzle blast upwards. I expect that muzzle brake design wuld influence the degree of obscuration caused in dusty conditions, but have no further information.

    Finally, as with so many things, a lot depends on the training of the tank crew or gun detachment. As a navy cadet, I remember doing one minute’s rapid loading of the old 4.5-in Mk 6. This was a separate-loading gun, with one loading number for shells and another for cartridges. Firing HE fuze VT (high) for policy air, the fuze-setting step of the loading process was skipped — the shell loader just hoiked the 25-Kg projectile out of the hoist and whacked it on to the loading tray, hoping the cartridge loader had got his (lighter) cartridge there first, then whacked the rammer button with both hands. A bunch of kiddie cadets on their first day managed a rate of 12 rounds a minute per barrel for one minute; I’m told a proper gun crew would have managed 15 or better.

    We did have the advantage of an automatic rammer (which partially made up for the separate loading) and hoists which put the projectiles and cartridges just where we wanted them. A tank loader is going to have a lot of fun getting hold of rounds once the ready-use rack is empty, expecially as sensible tank designers try to carry as little ammunition as possible above the turret ring.

    All the best,

    John.

    #40544
    Ivan Sorensen
    Participant

    Appreciate your thorough reply. A lot of factors to consider for sure.

    Your point on the ready rack is well taken too. Between easily accessible ammo being exhausted quickly and the casings littering up the turret floor, things would slow down significantly over time.

    Nordic Weasel Games
    https://www.wargamevault.com/browse/pub/5701/Nordic-Weasel-Games?src=browse5701

    #40546
    Les Hammond
    Participant

    A bit off-topic but the early war French tanks that had one-man turrets have surely got to be penalised in the rules in various ways (ROF, spotting, etc)

    6mm France 1940

    http://les1940.blogspot.co.uk/
    https://www.facebook.com/groups/386297688467965/

    #40669
    kavita1
    Participant

    Aye – same with some of the Russian WW2 tanks with 2-man turrets and lack of radios

Viewing 5 posts - 1 through 5 (of 5 total)
  • You must be logged in to reply to this topic.