Nice 2 Inch British Mortar Shell Any info is appreciated.

[AE501]

TimG

The 55 gr Ballistite Mk 1 or 2 and the 50 gr Balistite (smokeless) Mk 1 were both used with the Bomb 2" Mortar Bomb Thrower Mk 1, for long range, but also with other bombs.
Cart 18 gr Ballistite Mk 1 and 17 gr Ballistite or 81mm Hercules Mk 2 were also used with the Mk 1 bomb.
It depended on whether you tactically wanted the smoke at your end or their end according to fighting circumstances.
There were changes to the tail types used in the 1954 amendments, mainly aluminium tails were no longer used. I never remember seeing aluminium tails from 1957 onwards.
There was also a Bomb 2" Bomb Thrower Smoke Bursting WP Mk 3 which used similar cartridges. This bomb started as both 2" Mor and 2" Bomb Thrower, but the infantry had no use for it so it was soon marked as I just described it.

Bil

 

[AE501]

I said that the 73 gr was for use with Bombs 2" Mortar Signal Success, but this is incorrect. Signal Success used the Cart ML Mortar (smokeless) 50 gr Mk 1, as did the Grapnel 2" Mortar, Actuating Trip Wire, Mk 1. The Projectile, Cordtex, Anti Trip Wire, 2" Mortar Mk 1 used the Cart 2" Mortar 55 gr Ballistite Mk 2. I can find no reference for the use of a Cartridge 2' Mortar 73 gr, but it was listed in the attempted table.

In amendment 1 of 1954, it states that all Canadian cartridge bodies were stencilled in black, rather than the colours given in the other attempted table.

 

[TimG]

AE501,

I think we're talking at cross purposes. The point I was trying to make about the blue marked boxes is that they were for Long Range bombs for Bomb Throwers (modified), converted from normal Bomb Thrower bombs by changing the cartridge.

The early Signal Success did use a 73 gr cartridge.

TimG

 

[Bonnex]

Tim,
i am intrigued by the very last line on the last image (WS9/BM etc) which I take to be the authority for the conversion outlined in the text.

WS9 (Warlike Stores 9) was effectively the predecessor of DLSA. Is the Précis from Bramley?

 

[TimG]

N.

I think India, not Bramley. The Précis is from Don. Henderson, there are a lot of Kirkee documents with it, so I presume he did his I.O.O.s course there. There are a number of references to WS9. I will enquire.

TimG

 

[AE501]

Thank you for that TimG. I knew I had seen that the 73 gr was used with the Signal Success somewhere but I could not find it again.

 

[BMG50]

It seems its a No3; steel tail they use for the 73 grain signal success, i have a tec drawing of it.

 

[TimG]

The Précis states Tail Unit No.5 (Steel with Twenty One (21) holes).

TimG

 

[BMG50]

You are correct with the No:5 steel tail unit, the sectioned drawing shows a No:3. The 73 grn cartridge made in small numbers had a green cardboard casing with red writing marked as Mk1. Both round and cartridge I suspect would be the ultimate 2" mortar find. The only No:5 steel tail units I have come across are all with a 1950 date. Although my info is dated October 45 the earliest date for a No:4 tail is 10/43 which I have in my collection. Would be nice to have tail production dates to see when steel tails were made. Seems pointless to make No: 3 and 4 tails at the same time. I guess that the No:3 was manufactured around 42 not sure if production of this tail stopped as soon as the No:4 came out making the No:3 much rarer.

 

[AE501]

If you have stocks of No 3s being used on production runs, you use these up.
In the meantime No 4s are being used for depot repair programmes, on non convertible aluminium tails, and on mazak tailed bombs in tropical stations, which are liable to mazak poisoning. When the No 3s run out at production, No 4s are used.

 

[BMG50]

'Liable to Mazak poisoning' can you enlighten.

 

[TimG]

Inter–Crystalline Corrosion

"The origin of these troubles was unknown until systematic research was applied to the problem. It was then found that the deterioration which occurred on ageing was due to inter–crystalline corrosion.

Nearly all metals are subject to corrosion to a greater or lesser extent, as, for example, the rusting of iron or the tarnishing of silver, but in such cases the corrosive attack is general and proceeds inwards more or less uniformly. In the case of inter–Crystalline corrosion the attack is selective, and is concentrated at the boundaries of the individual crystals or grains of the metal

Such an attack is obviously more dangerous than general corrosion. As penetration proceeds, a bulky product is formed between the grains which tends to cause distortion and disintegration. The deposit formed is easily permeated by the advancing corrosive agents, and so the attack proceeds.

A number of metals and alloys are subject to inter–crystalline corrosion, but the cause is not always the same. In some cases it arises from conditions of internal stress – in others impurities are responsible. Zinc die casting alloys belong to the latter class, and in their case the harmful impurities likely to be encountered are lead, tin and cadmium.

If these impurities are reduced below definite limits the alloys remain permanently unaffected even by warm, humid atmospheres in which the attack is naturally accelerated. If, however, the impurity content is allowed to exceed even to a slight degree the rigid limits laid down in the appropriate specifications, inter–crystalline corrosion can occur relatively rapidly even in conditions of normal atmospheric humidity."

MAZAK. 1952 Imperial Smelting Corporation Limited.

 

[BMG50]

Ahh I see, I thought it was something to do with Mazak poisoning the environment not the deterioration of the strength and stresses that would affect its performance upon firing. I do have a No:2 tail fin that has cracks and flaws in it unfired, either a bad casting or cast too hot or cold.