Interesting question as there was only one(?) prototype of a supposed L2A4 gun. And it was going to be the Fazakerley made variant of the L2A3. That's the easy answer though........ The Fazakerley 'pirated' gun was secretly named the PIONEER or the XLxx something or other. Mind you, there were several versions of this theory. Some papers call the Canadiangun the L2A4 while others suggest that the L2A4 was going to be the UK
version with the L1A1 rifle bayonet fitting. So you take your choice.......