Anything that you can not buy in a convenience store on Canada Day is illegal in Canada.
Even the allowable fireworks are under scrutiny at the moment in this nation, so it's really best not to tempt fate.
Regardless of where/ how you bought explosives of any kind it is very very illegal to tamper with them in any way as it will then count as an 'improvised explosive/ ordnance device' for the purposes of Canadian Law.
The long and the short of it is, it's really not worth messing with.
Sure, you might get away with it and even be relatively safe... But do you really want to be that guy who associated illegal explosives with Airsoft?