Sten project

[tiriaq]

If you search this site, you will find a long closed thread detailing the building of semi auto Mk. II clones which were successfully registered as restricted firearms based on barrel length. These were inspected and approved by the powers that be. Mechanically, the breech mechanism has much in common with that of the Cooey 64 .22 rifle. Presumably a gun with the same operating system and a barrel exceeding 18.5" would be non-restricted. It would also be a rather ungainly thing. I would suggest that should you build such a thing you be prepared to demonstrate that it is unquestionably semi auto only, because anyone seeing it is going to assume otherwise.
There is no real supply of Mk.III or Mk.V kits in Canada. There are some Mk.II parts which turn up from time to time.
The semi auto bolt system in the thread I mentioned is long out of production. There is a better mechanism produced by Indianapolis Ordnance in the US. IO will not export to you.