Question about the No 1 Mk 5

[964AWACS]

Does anyone know the purpose of the single "nub" on the barrel? It does not seem like it would have been used to lock the barrel into a port - I would think that you would need 2 or more opposing lugs/nubs to be effective.

[HoosierFlare]

Anyone? I would like to know the answer to this question as well.

[billybibbet]

I saw a post somewhere online that it was to retain a barrel extension, to lengthen the barrel. The post included a picture of the barrel extension...unfortunately I did not save the link. Well what do you know? I just ran across a post in this forum, with pictures!
http://flaregunforum.com/viewtopic.php?f=7&t=684

[964AWACS]

Interesting. I wouldn't have thought that one lug would stabilize a barrel extension/attachment. I would have been wrong!