Shell casing ID help needed.

[mikerock]

I have been asked to help ID these two shell casings. Their age is unknown.

1) diameter at case neck - 26mm
2) overall length - 94mm
3) diameter at base - 30mm
4) diameter of primer pocket on the base - 13mm

The stampings on the base read:

M
over
Vm


Thanks in advance for any help!

 

[green]

1" Aiming Rifle a subcalibre ctg used in British Empire artillery c1890-1950.

 

[mikerock]

Thanks!

Would this have been used in a different types of artillery pieces?