25x173 rounds

[Nabob]

This would be a question mainly for Mr Tony Williams, but please anyone else feel free to respond.

I am curious about the designation of the 25mm KBB or KBD rounds.
I have read the Rapid Fire, but there You mention only the 25x184 case length, sir.
There is also Your post from 2012 here: https://forum.cartridgecollectors.org/t/25x181kbb-apds-t-now-sectioned/10922/5

I actually have two variants of the drill round and the case length is the same as 30x173.

Could You please enlighten me on the origin of this designation?
Best Regards, Bob.

 

[Tony Williams]

The earliest published mention of the cartridge I have is in Jane's Directory of Military Small Arms Ammunition by Ian Hogg, published in 1985, and that states that the case length is 184mm. I suspect that this is the source of later statements (including my own in Rapid Fire).

I have since acquired an AMDS round and the case length (which I have just measured) is 182.5mm.

 

[Nabob]

Thank you for the swift answer sir.
Attached are the pics of the drill rounds together with 30x173 case.
The case of the 25mm length is also 173mm.
From the pictures on the web one can see the different lengths of the case neck with different projectiles.
Bob