Just to clairfy
It is not illegal to have firearms in your backyard,in the backseat of your car or for that matter in your hand walking down the street. With exception of restricted which have a boatload of requirements for transport.
Will the police be called possibly depending on here you live and who your neighbors are.
Discharging is a city bylaw which can and often does change without notice, now in all fairness you can call your local police dept who will most likely know and this fellow should have done so. But by the same virtue the city should regularly print that bylaw, many people my age would not assume it included pellet or bb guns, and for that matter it may include bow and crossbows
Should the fellow have done hi homework sure, but be clear hiding everything so some busy body does not get their panties in a knot is not a good way to live. Know the law, your rights and do anything you are allowed to do with in those boundaries.
It may occasionally lead to a meeting with your local police, but assuming you have all your required paperwork and copies of any legal stuff. It should be short and painless. I do not expect the police to be up to date on every single piece of federal province and municipal legislation, but if it effects me I should be.