3-inch mortar - changes in weights of component parts

Discussion in 'Weapons, Technology & Equipment' started by Gary Kennedy, Jul 23, 2021.

  1. Gary Kennedy

    Gary Kennedy Member

    I was having a look back at the info I'd got for the equipment of the British Infantry Battalion, prior to making some updates and corrections. I realised I had 'swerved' any weights for the 3-inch mortar, so had a check back through sources and remembered why that was. I have had a good search through the Canadian online sources and compared against other info available. I thought if anyone might care about answering the question they were likely to travel through WW2Talk at some point, so thought I'd put the chronology up here and see if anyone wants to throw rotten fruit at it...

    Early war there are two documents of importance, both available online in various places I think.

    Handbook for the Ordnance, ML 3-inch Mortar, MkII (Aug 1937)
    SAT Vol I, Pam 9, Mortar 3-inch (1939) (Jan 1940)

    The former gives component weights as;
    Mortar barrel - 44lbs
    Mounting (bipod) - 44lbs 9oz
    Base plate - 37lbs

    The latter gives loads for Nos.1 to 3 inclusive as;
    No.2 (barrel & spares) - 44lbs
    No.3 (bipod) - 44lbs 8oz
    No.1 (base plate & sight) - 37lbs

    Straight off there's a little quibble there, as the Handbook gives no weight for the sight and the SAT Pam suggests it's counted with the load of the No.1, however he only seems to have the weight of the base plate included in his load.

    Scroll on to the venerable US Army publication TM 30-410 (Handbook on the British Army, etc... September 1942), which gives the following component weights.
    Mortar - 42lbs
    Mounting - 45lbs
    Base plate - 37lbs
    Total - 124lbs

    There was then a great deal of time and effort invested in increasing the range of the 3-inch mortar, from an admitted unimpressive maximum of 1600 yards, to closer to 3000 yards. In the event the max range acknowledged was around 2800 yards (2750 in some quarters), which finally allowed it to outrange the 8-cm Granatwerfer 34 which had a range of 2400 metres (circa 2625 yards).

    SAT Vol I, Pam9 (1944) (Mar 1944) gives updated loads for Nos.1 to 3, but not component weights;
    No.2 (barrel & spares) - 51lbs
    No.3 (bipod) - 44lbs 8oz
    No.1 (base plate & sight) - 52lbs

    Clicking robotically through the Canadiana Website offerings, the following individual component weights are offered;

    Mortar (Mk2) - 43lbs
    Mortar (Mk4) - 43lbs
    Mortar (Mk5) - no weight given, 'similar' to Mk4

    Base plate (No.1 Mk1) - 37lbs
    Base plate (No.1 Mk1A) - 34lbs (airborne use)
    Base plate (No.1 Mk1B) - 41lbs (strengthened)
    Base plate (No.3 Mk1) - as per No.1 Mk1A
    Base plate (No.4 Mk1) - as per No.1 Mk1B
    Base plate (No.5 Mk1) - 43lbs
    Base plate (No.6 Mk1) - 34lbs (late war equipment, mentioned in particular for use in Far East)

    Mounting (Mk.1) - 45lbs
    Mounting (Mk.2) - no weight given, 'similar' to No.1
    Mounting (Mk.2X - ?) - 44lbs 8oz
    Mounting (Mk.3) - 44lbs 9oz
    Mounting (Mk.4) - no weight given, for special roles, designed by Messrs Jowett Cars Ltd
    Mounting (Mk.5) - weight given as 34 to 36lbs AND corrected to 44lbs

    Sight unit mentioned as approx 5lbs, case 1lb.

    A revised three-man load from (I think) early 1946 gives weights of;
    No.2 (barrel, with recoil system, cover) - 40lbs 8oz (spares not included in figure)
    No.3 (bipod, less recoil system) - 36lbs
    No.1 (base plate plus sights) - 40lbs (as 34 + 6)

    Complicated 'innit?

    Gary
     
    CL1 and Alex1975uk like this.
  2. CL1

    CL1 116th LAA and 92nd (Loyals) LAA,Royal Artillery

    Well done Gary for posting
    Weighty to lug
     

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