Is this part of a Depth Charge Pistol?

[ron3350]

I bought this as a depth charge fuze? Now I think it is part of a Pistol?

It is marked:

MARK 1 F. A (arrow) N K in a circle. So it is Australian.
Made from brass and Bakelite.
Top unscrews to expose a detonator tube. Bits obviously missing.

Base is 54mm. Centre is 38mm. Length is 126mm overall.
I have little knowledge on this item . How is it used? Thanks. Ron.

 

[Michel]

Since I have never got a reply on my question I will follow this one!

http://www.bocn.co.uk/vbforum/threads/94254-Seamine-detonator

 

[ron3350]

Michel
That makes two similar items so hopefully someone will identify them for us.
Mine is the same inside, I forgot to unscrew it for a photo. Where are the experts? Thanks for the reply.

 

[Natter]

I've put the answer here:
http://www.bocn.co.uk/vbforum/threads/94254-Seamine-detonator?p=300687#post300687