QF 2 pounder (40x304R), England, WW2

[tankbarrell]

I've had the pictures of the XB barrel and compared it to my IX.
The diameter and bevel are the same and the radius from the main tube to muzzle swell are also the same. The only difference, apart from the keyway, is the length of the muzzle swell. The XB barrel is 3" long and my IX is 3.2" long. Obviously, this is a critical dimension for the Littlejohn adaptor.

 

[ThomasP]

Interesting.

There would be some 'play' built into the design, so I wonder what the high/low tolerance was for the length of the muzzle swell/flange, as well as how far the engraved line was supposed to be behind the collar?

I cannot make out the engraved line on the XB barrel in the photo, is it visible in the original image?

 

[tankbarrell]

The pics I was sent are fairly low res so I can't see the line. There are also a couple of coats of paint... Next time I see that gun, I will have a closer look.
A small tolerance would be expected but 0.2" longer would mean the equivalent amount less thread engagement which would not be desirable.

 

[Basilisk]

I live in Australia and have never seen or heard of a 2Pr cannister round. (I doubt it exists so would love to see it).
I have a factory sectioned HE-T round.

Two of them, the re-purposed 37mm canister already mentioned, and the 2pdr case shot which seems to have been a really heavy duty water proofed cardboard tube filled with shot but beyond that description I've not seen much else about it so far.