Mills no 36 collar

[SG500]

Not quite my area of expertise but the attached info explains it all.
5th photo shows the grenade with the pin removed and the collar holds the lever in place.
6th photo shows a view of the pin in place but no collar - a large gap between the pin and the lever.
8th photo shows the collar partly inserted into the 2 grooves in the grenade, 9th photo fully inserted.
Dave.

 

[Snufkin]

About three or four of those examples are known to exist. It cropped up a couple of years ago in a discussion on Irish grenades...

https://www.bocn.co.uk/threads/irish-grenade-mmmm.83356/#post-208606