25 pounder shell casing

[Adrian Harris]

Still not having a lot of luck with the KwK shell casing dimensions, so I though I'd have a go at the 25 pounder.

The casing is cylindrical at 14.6mm, but a website I've just found seems to think they should be tapered, so I'll have a go at that next.

The wall thickness started at 0.8mm and the last I tried was 0.425mm. There doesn't appear to be any noticeable deformation, so I'll also try one at 0.25mm.

One bugbear is that the breech ring in the kit appears to have a standard 1/2" (12.7mm) diameter aperture, so the shells won't fit. Trying to make that big enough to fit looks like a bit of a challenge too, due to the way the breech and the barrel mate.

Adrian.

[martin pitcairn]

Hi Adrian,
I just happen to have a 25lber casing, All sorts of marking on the base, here are a few CY06/85 030 030 3BN 85 IIMK4 MK2/1 25P PLB 1A. The base is 104mm across 4mm thick, step 3mm high by 1mm thick, 285 mm length from top of step 292mm overall length.
I make the top 90mm across, skin 1mm thick The tapper looks approx. 3mm over the length ie base excluding step 96mm top 90mm therefore 3mm over 285mm

Hope this helps

martin

[martin pitcairn]

Picture of the base

[martin pitcairn]

picture of the side, including small step at base,

[Adrian Harris]

Many thanks for the details Martin - I'll check them out in a moment.

Here is the latest casing.

1mm taper from one end to the other, with the open end wall 0.25mm thick.

Adrian.

[Adrian Harris]

Last go for the time being as I'm all out of 3/4" brass bar

On the left is the casing done to Martin's dimensions, compared to the previous tapered one.

A flash shot shows up the machining marks, so I need to work on the programming to try and make the final cut smoother.

Adrian.