3" Mortar information

[Darrin Wright]

I have several questions related to 3" Mortar and associated CES that goes with them.
By asking my questions in this thread, I hope to learn and build an information base for those that have info and require info.

Base plates
I have attached several pics showing a rectangular base plate and a plate with tapered corners/edges. Why is this?
I have heard that there was a modification/build change late in the war and that all early base plates were scrapped and replaced with the new rectangular model base plate?

How many aiming posts are utilised with the mortar?

[lynx42]

Hi Darrin,

My 3" mortar has the later base plate as pictured in two of your photos. I have no idea when the change took place. It will be interesting to see the reply's. I have 2 aiming posts and lights in the CES kit for mine.

Regards Rick.

[Mike Cecil]

Darrin,

Try the following NAA files, they may provide an answer. Some are open, some are scanned, a few are closed (NYE) (you'll have to apply to have them opened):

NAA Barcode: (use advanced search)
365436
448758
1039482 - NYE
1039484 - NYE
4330497
4330876

I only have the Aust 1937 training pam, which is not provide much.

Mike

[Tim Bell]

Always believed the base plate with holes in was lightened for Airborne use.

Tim

[Lynn Eades]

Are we talking about Australian made 3" mortars, in this thread?
I'm guessing there were variations. New Zealand Railways built them here.
(I know nothing about them and have just posted for clarity)

[Bruce Parker (RIP)]

British 3" made in 1944. The base plate has no holes or tapers around the edges and has a chain at the back for lifting instead of rope. The leather case is C/|\ marked but had a slip of paper inside with Greek instructions.

And it's little brother. Does anyone out there know where I can get a muzzle cap for a 2" mortar?

I have a copy of the 3" manual if there's anything specific you'd like to hear about.

[rob love]

Originally Posted by Bruce Parker

Does anyone out there know where I can get a muzzle cap for a 2" mortar?

BRP in the US used to have them listed separately, but I only see them listed as part of a group of parts now. http://www.brpguns.com/mortar-parts-lot/

You can also order them from Westland military, likely the same place you got your 2" mortar sight from: http://westland.nl/product/2inch1

[Darrin Wright]

I have a electronic Aust Army manual, dated 1972, that features the rectangular base plate with a white line painted on it (which is the same as pics posted).

I have no information, except for the WW2 BGC Mortar vehicle book/pics, that shows the base plate with tapered edges.

I am happy to see different variations, from different countries, that depict various builds & uses. Its all an education.

[rob love]

Here are a couple shots of various 3" baseplates. The early one is currently on ebay through Westland military antiques at only £550 ($900 cdn or so). The second one shown is from the Australian War Memorial website, and the third is off a 3" mortar presently available from Collectors source here in Canada. The last shot is a scan from the 1937 manual for the 3" mortar.

My 3" mortar has the baseplate as pictured from collector's source......small holes and the chain for dragging it around.

[welbike]

Hi Guys,

Have found some chests in the garage, and was wondering if they are for 3" mortar bombs, as someone suggested when I bought them.









Are they??? have 3, all for sale, can bring to UK.

Cheers,

Lex

[Ed Storey]

Interesting wooden box but I doubt it is for 3-In mortar bombs as the bombs were delivered in cardboard tubes, strapped together so that they could be carried in groups of three. These tubes were then shipping in either wooden or metal boxes; two sets of three - 6 bombs to a box.

[welbike]

Well Ed, I don't know, that's why I posted it here! the cubicles are slightly over 3" square (80mm) and a total of about 14" (360mm) deep.

Here a better picture of the lable;



Date is 1976, were they still used by then??

Cheers,

Lex

[Ed Storey]

The M.L. 3-In Mortar was replaced in the mid-1950s by the 81mm Mortar. Is there a marking on the bottom of the box, perhaps something like as an example B.103?

[Godwin Hampton]

Darrin, the 1951 Infantry Training pamphlet for the 3" Mortar shows a barrel with a removable breech piece, describing it as the Mk 5 barrel. The square baseplate with large holes and a chain handle at the rear of the top plate is called the No. 6 baseplate, and finally the bipod having stamped plates ( rather than forged ) joining the 2 legs to the elevating screw tube is described as the Mk 5 bipod.

Now these different versions of these 3 items could probably all be used together interchangably! So you could have a mortar having a Mk 3 barrel, a No 4 baseplate and a Mk 1 bipod!

The Small Arms Training pamphlets for 1939 and 1943 show the one-piece tube, the tapered corner baseplate and the bipod with forged horizontals joining the legs, without giving any marks or numbers.

The 1937 Handbook ( reprinted by The Naval and Military Press and very informative! ) probably issued when the mortar was accepted for service starts with the Mk 1 barrel, but gives no marks or numbers for the baseplate and bipod shown.

There were, thankfully, only 2 marks of sight which have a different mounting system so this also entails differences in the bipod sight supporting bracket.

So to simplify I divide the 3 inch ( actually 81mm ) mortar versions broadly into two types, the early with the one-piece tube, tapered baseplate and forged bipod and the later type with removable breech piece, square baseplate and stamped bipod.

[Mike Cecil]

Darrin,

I have some information on the 3 inch mortar base plates pertaining to Australia:

(1) pre-war and early war base plate Mk.1: as per the image in the Mortar Carrier handbook. Same as the Brit mortar plate.
(2) circa May 1943 introduction of the No.4 Mk1 base plate: essentially the same shape as the Mk.1, but with increased ribs and strengthening pieces to cope with higher incremental charges, as the Mk.1 was found to bend when firing higher charges. Most obvious differences were underneath, where there was substantial increased ribbing (and greater weight!). This appears to be the one illustrated in the book page image posted by Rob Love (above).
(3) In early 1945, certainly before June 1945: introduction of the base plate No.6 Mk.1(Aust), which is the square one with the two rope handles, as seen with mortars issued post-war. The plate was introduced to cope with the increased recoil of higher incremental charges and to be several pounds lighter in weight than the No4 Mk1. This remained the service base plate post-war until the withdrawal from service of the 3 inch mortar.

I'd suggest that finding either a Mk.1 or No.4 Mk1 base plate in Australia will be very difficult. You perhaps might find one overseas.... then you have to get it to Oz .... and past customs.

Regards

Mike

[David Perrott]

Hi all i have a pair of NOS storage tubes ie 2 lots of 3 in there original crate for sale if anyone is interested they are 42 and 43 dated.

cheers dave

[welbike]

Originally Posted by Ed Storey

The M.L. 3-In Mortar was replaced in the mid-1950s by the 81mm Mortar. Is there a marking on the bottom of the box, perhaps something like as an example B.103?

Ed, cannot find anything on the one box, will check the others though.

On the Subject of sights, have some sights f/s. too, marked 4.2" but believe they are same as 3"

Cheers,

Lex

[Darrin Wright]

Thanks all, now I have an understanding of what & when with the various mortar items.
I think it would be quite hard to find the correct early baseplate, then the cost would possibly make me cry.

Reading the trg pams, I think there are 2 aiming posts with each mortar.

Posting some pics of sights that I have found on Ebay for interest.

[Darrin Wright]

a couple of pics from Ebay of a bi-pod.

What Mk is this?

[Darrin Wright]

another pic showing the aiming posts and tube cleaning rod.
This is Colin's Mortar Carrier that appeared at Corowa some years ago.

What colour are the aiming posts painted?

Do others have pics out there to add to the variety of equipment used with the mortar? nationality does not matter, but would be good to highlight the differences.

[colin jones]

Hi Darrin, one is obviously black and white and the other is very fire engine red and white. They are both originals, great job on the carrier by the way.

[Darrin Wright]

Thanks Colin for the confirmation of the post's colour. I wasn't sure if they were original or had been touched up.
How are your projects going?

[Chevrolet 41]

Hi All,

I understand the white stripe on the base plate provided direction for night shooting so the crewmen knew the direction to lay the base plate down i.e. in the direction they were going to drop some ordanance.

Just glad I never had to carry the bipod any distance!

Cheers

[Godwin Hampton]

Chevrolet41

My impression is that the white line was added post-war.

The white line was NOT for aiming the mortar at night - for that you had the night aiming lamp - but for aligning the base plate with the 'zero line'.

The section commander would decide where to site the mortar/s and would plant a small flag. He would then establish the direction of the target from the flag, and an aiming post would be planted away from the site. So the imaginary line flag - post - target would be the 'zero line'.

The base plate would then be placed close to the flag, with the white line in line with the flag and the post i.e. on the 'zero line'. The flag was then removed.

The white line was offset to be in line with the sight, not the barrel, as you aim with the sight! The offset would make no difference at the target....you would not be sniping with a 3" Mortar!