I found this and the stag 10 would be considered a semi longgun but Iam no expert by any means
Magazine capacity
Some large-capacity magazines are prohibited regardless of the class of firearm. As a general rule, the maximum magazine capacity is:
5 cartridges for most magazines designed for a semi-automatic centre-fire, long gun
10 cartridges for most handgun magazines
A large-capacity magazine is not prohibited if it has been permanently altered so that it cannot hold more than the number of cartridges allowed by law. Acceptable ways to alter a magazine are set out in the Criminal Code Regulations.
There is no limit to the magazine capacity for semi-automatic, rim-fire long guns, or for other long guns that are not semi-automatics, with some exceptions.
http://www.rcmp-grc.gc.ca/en/firearms/specific-types-firearms#mc