12pdr 12cwt cut down query

[SG500]

This case measures 190mm long, with a rim diameter of 104mm. The mouth is 82mm.
Head stamp as shown. Clearly its had a busy life.
I'm thinking its some sort of depth charge or torpedo implulse cartridge but is not quite the same as the one on the link below.
Anyone have any ideas?
Dave.

http://www.bocn.co.uk/vbforum/threa...-25-oz-torpedo-impulse-case?highlight=impulse

 

[Burney Davis]

The dimensions you give match the 12pr 8cwt case Dave but the primer for that case is the typical 'protruding primer' type found in the 12pr 12cwt case, not the number 19. It is not unusual for cases to be modified by the primer pocket being re-bored, but I can't find reference for it being done to the 8cwt case.

 

[tigbrand]

To use this case in the 12pdr breech would cause issues I imagine as its made to take the adaptor. Looking at the link, I would assume you are right in thinking an impulse cart of some type, with a smaller charge,
As 12pdr is barred out its not for that anyway. The A/S 10 mortar uses the 3" 20cwt or 77mm case which is similar in size but still different. It says HMS Swiftsure and Triumph used adaptors in the cases. I suppose the clue is No3 MkI. Interesting case Dave.