From the Natural Resources website:
Storage for Use
Dwelling
A person may acquire and store up to 225 kilograms net explosives quantity of ammunition for use in a dwelling.
When small arms cartridges are stored in a dwelling:
a.they must be stored away from flammable substances and sources of ignition. People not authorized by the retailer must not be given unlimited access to the cartridges.
Storage Unit
A person may acquire and store up to 225 kilograms net explosives quantity of ammunition for use in a storage unit.
When small arms cartridges are stored in a storage unit:
a.the storage unit must be located in a dry place, away from flammable substances and sources of ignition;
b.the storage unit must be constructed and maintained to prevent unauthorized access and to protect the contents from weather;
c.if the storage unit is a container, it must not impede exit in case of fire;
d.if the storage unit is not a container, all exits must be kept unobstructed;
e.any shelving in the storage unit must be made from a non-sparking material (for example, wood or painted metal);
f.nothing other than propellant powder and percussion caps may be stored with the small arms cartridges;
g.small arms cartridges, propellant powder and percussion caps must be stored separately from one another (for example, on different shelves or separated by a wooden barrier);
h.the storage unit must be attended when it is unlocked;
i.the storage unit must be kept clean, dry, organized and free of grit;
j.any spill, leakage or other contamination in the storage unit must be cleaned up immediately;
k.precautions that minimize the likelihood of fire in or near the storage unit must be taken; and
l.a sign that displays the words “Danger — Fire Hazard/Risque d’incendie” in letters at least 10 cm high and that prohibits smoking using letters, or a symbol, at least 10 cm high must be posted on the storage unit in a clearly visible location.
https://www.nrcan.gc.ca/explosives/acquisition-storage-sale/9833
How much is 225 kg NEQ?
From the CBSA site: 225 kg Net Explosives Quantity (NEQ) which is about 1,000,000 rounds of pistol or 100,000 rounds or rifle, or 100,000 rounds of shotgun shells
http://www.cbsa-asfc.gc.ca/publications/dm-md/d19/d19-6-1-eng.html