Is this an Adaptor Ring?

[Shipwreck]

Hi,

I saw something similar in an earlier post which looked familiar. Can anyone confirm if this is an adaptor ring, and if so what was it's purpose please?

The internal diameter of the threaded side is 2" On the other looks to be a small square, but I cannot make out the letter within.

Many thanks.
 

[Spaceman]

Looks a bit like the cap used to protect the mounting thread on the top of a tripod. I have a number of heliograph tripods and, although the thread diameter is much smaller, the cap is not that different. These heliograph caps have a rotating captive stud in the centre with a chain attached fixed to the tripod at the other end.

[butler]

Not an expert but, Base of the nose fuse on an 18lb shrapnel shell. It should have a hole on the outer ring for a C spanner to fit into 

[Spaceman]

It doesn't look like anything from a No. 80 Shrapnel shell time and percussion fuse?

[butler]

As I said I'm not an expert but I have one at home. I'ts shown on the far right in the attached photo and sits below the graduated ring which is shown to its left. All the parts fit together and come from an 18 lb schrapnel shell

[peregrinvs]

Yes, it’s the part that connects a No.80 or No.85 time and percussion fuze to a 13 or 18 Pounder shrapnel shell. The fuze and adapter ring usually separate in one piece from the shell when it detonates.

[AOK4]

11 hours ago, peregrinvs said:

Yes, it’s the part that connects a No.80 or No.85 time and percussion fuze to a 13 or 18 Pounder shrapnel shell. The fuze and adapter ring usually separate in one piece from the shell when it detonates.

Not always though, but the plate with the hole usually detaches from the ring.

[Shipwreck]

Thanks everyone for your contribution. I'm labeling it as coming from a 13 or 18 Pounder shrapnel shell, & part of a No.80 or No.85 time and percussion fuse. And yes butler, it does have a hole in the side which has rusted over.

I've been reading though comments in the "Arms and other weapons" group (I'm up to page 50) and I'm very impressed by the knowledge coming from the group. Thank you so much for your help. I do have a few other things to show, along with some more questions. But I will spend some more time researching before doing so. Keeps me busy in retirement!