Apparently from reading the "look at the weird/cool stuff we can have in Canada, despite our overall crappier gun laws" threads and show-n-tell pictures on gun forums, that's what everyone with EBR's in Canada does, by that I mean the suppliers. Very simple blocks and rivets are all that are required.
If SHTF, everyone knows 1 second with a drill, 5 with a Dremel, or 20 with a file is all that's needed, and they have 20-30 rounds on tap.