2" British mortar lanyard

[Topfmine]

I think the lensatic sight went out of use very early in the war, quite a complicated bit of kit (seen one on eBay not that long ago and didn't reach reserve even at £1200).
My explanation of the so-called flare barrel which I mean a rim around the muzzle end which you correctly explained is what I was trying to put in words.
Quite a few variations to the mortar since it was introduced especially the breach and barrel threading, first the threads were fine continuous, then course square continuous then course square and interrupted. The course continuous and interrupted can be used together.
Actual as you say there is quite a lot of info about this mortar, different variations, loads of interesting developments with the rounds it fired especially interesting notes about the tail units (I always thought until recently that the No:4 tail unit seen on most post war rounds was a post war improvement over the steel No :3 tail unit of war time use. I just bought three mint para illum and one white multi star rounds at the war and peace show all with No: 4 tail units marked S&W dated 43, 44 and 45. Just goes to show you learn more as time goes by)
I was, years ago going to write a book about the 2"mortar but there was so much to write it would have been thicker than your Sten gun book you done and that doesn't include the Mk 1 trench 2" mortar of WW 1 that fired the toffee apple bombs.
I think I will have buy myself an anorak.