Help Please to identify unusual WW1 Cartridge - Battlefield Found Somme

[r3jmk]

Any assitance out there to identify this small stubby bullet like object found on the Somme - Mouquet Farm area:

Looks very like a pistol round but isn't, not sure if it is a artillery primer, mortar primer, flare or firearm related. Item is brass, bottom looks like small slotted grub screw where I would expect a primer to be, it appears to be triple crimped at the thread to stop it moving. It has a rounded off top that appears to capture the main body inside and prevent it from coming out.

I have a very similar item found at Mametz a few years ago and is a the shell only with nothing in it which suggests that the recent find is in 2 parts and is designed to come apart. At first I thought it was a blank .455 round but you will see in the comparison pic that it is not.

Any assistance would be very useful as I have never encountered an item like this before.

Many thanks

[r3jmk]

Absolutely no markings on this by the way - no head stamp which leads me to think it is not a bullet by a primer of some description.

r3jmk

[TonyE]

It is certainly not a cartridge for small arms. It could be part of a fuze but I am not sure.

There is something vaguely familiar about it but I can't remember exactly what!

Maybe the synapses will fire better later.

Regards
TonyE