Simple answer... detachable magazines are allowed in Canada. Never been an issue.
Long answer...
Are you really REALLY sure you want to delve into the world of Canadian gun laws as they pertain to magazines??? DO YOU??? ALRIGHT. Here we go...
Magazines are regulated apart from firearms under the criminal code. The are either prohibited, or not regulated. They don't fall under the firearms classifications of non-restricted, restricted and prohibited.
As a general rule magazines that are "built and designed for use in a pistol that is commonly available in Canada" are limited to 10 rounds.
As a general rule magazines that are "built and designed for use in a semi-auto center fire rifle that is commonly available in Canada" are limited to 5 rounds.
As a general rule magazines that are "built and designed for use in a rimfire rifle or manual action rifle or shotgun that is commonly available in Canada" have no limit to their capacity.
Now here is where it gets a little confusing.
If a magazine is originally built for a pistol (ie not modified after the fact) and that magazine just happens to fit into a rifle, then the magazine does not make the gun or the magazine itself illegal.
Example...
The Marlin model 45 (Camp Carbine) rifle chambered for 45 Auto caliber uses magazines designed and manufactured for the Colt 1911 handgun, therefore the seven round and eight round capacities are permitted. A similar example is the 10 round capacity magazine for the Rock River Arms LAR-15 pistol, regardless of the kind of firearm it is actually used in.
To muddy it up even more, magazines are only regulated to the type of ammunition they were designed to carry.
Example:
Heckler and Koch P7 pistol chambered for 9mm Luger caliber:
The magazine designed for the 40 S&W calibre variant of the pistol will hold 13 cartridges of 9mm Luger calibre and function in the 9mm Luger calibre P7 pistol. This is permissible as the maximum permitted capacity of the 40 S&W calibre magazine must be measured by the number of 40 S&W calibre cartridges it is capable of holding, which is 10 such cartridges in the case of the HK P7 pistol magazine.
Now if a magazine was designed for both use in a pistol, and a rifle of any type, the magazine must be limited to 10 rounds. ie rimfire pistol and rifle mag designed originally for use in both.
All very straight forward... no? For more info look here...
http://www.rcmp-grc.gc.ca/cfp-pcaf/bull ... 72-eng.htm
If you understand it in the first read, you didn't read close enough.