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The Great War (1914-1918) Forum

Remembered Today:

18pdr shrapnell shell gain tube


Guest charlie5729

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Guest charlie5729

When looking at various spent shells, there is sometimes left in the shell, the steel disc that was attached to the brass gain tube. How was this tube and steel disc fitted orignally, as the disc itself, is bigger than the threaded hole the fuse is screwed onto.

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When looking at various spent shells, there is sometimes left in the shell, the steel disc that was attached to the brass gain tube. How was this tube and steel disc fitted orignally, as the disc itself, is bigger than the threaded hole the fuse is screwed onto.

An interesting questiion does anyone know how the item was fitted. Could it possibly be done by heating one of the items up and freezing the other.Just an idea.

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The construction of the shrapnel bodies varies with calibre. On the 18 pdr the No.80 or 85 fuzes screw into a brass adapter which in turn screws into a 2.5 inch threaded hole in the nose. The steel plate (pusher)fits over a recess in the base of the shell which holds the black powder charge which propells the payload from the shell. Because the walls thickens towards the base of the shell the internal diameter is less there than at the nose. Once the fuze adapter is removed the plate should pass through. Other calibres have two piece bodies and the ogive screws onto the cylindrical section. This join is not usually visible due to paint or rust depending on condition. SW

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The construction of the shrapnel bodies varies with calibre. On the 18 pdr the No.80 or 85 fuzes screw into a brass adapter which in turn screws into a 2.5 inch threaded hole in the nose. The steel plate (pusher)fits over a recess in the base of the shell which holds the black powder charge which propells the payload from the shell. Because the walls thickens towards the base of the shell the internal diameter is less there than at the nose. Once the fuze adapter is removed the plate should pass through. Other calibres have two piece bodies and the ogive screws onto the cylindrical section. This join is not usually visible due to paint or rust depending on condition. SW

Hi S.W. Many thanks for your reply it is interesting to see how the shell releases its cargo.

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A sectioned 18pdr shell comprising of parts from the battlefield, even to the explosive container in the base which came from a source in Flanders. The "pusher plate" can be seen in red just above this container. Sectioned fuse for illustrative purposes.

9962629345_fa8a647c77_z.jpg

Image link with more info and images

https://www.flickr.com/photos/glosters/9962629345

Norman

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Thank you for posting that item, is it a genuine item that has been sectioned for display purposes or is it a model ?.

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Presumably the force of the expelling charge has to strip the brass thread on the adaptor through the iron one in the shell body? I've sometimes wondered if the force required to do that would deform at least the front balls so severely as to make the shrapnel pattern random and inconsistent? Wouldn't small brass shearpins be a better way to attach the fuze + adaptor?

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grandpacarr, on 07 May 2016 - 4:34 PM, said:grandpacarr, on 07 May 2016 - 4:34 PM, said:

Thank you for posting that item, is it a genuine item that has been sectioned for display purposes or is it a model ?.

Completely genuine and all parts are original except the detonator tube running from the fuse to the explosive charge. For obvious reasons the explosive container was the most difficult to get as these disintegrate upon discharge.

From the Somme

5138686771_91147f6067.jpg

Norman

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The lead/antimony bullets are held in resin and move forward en masse under the pressure of the steel plate until the pressure is sufficient to dislodge the adaptor. Probably the pressure is sufficient to cause the thin walls of the ogive to expand given that the payload is accelerated to a couple of hundred ft/sec or so in relation to the shell body. For Mike B; some shells such as the 4.5 inch howitzer shrapnel do have the ogive held to the lower section by rivets which are sheared when the charge is exploded. I am sure this has been covered elsewhere in the forum in some detail by persons more qualified than I. - SW

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