http://www.cbsa-asfc.gc.ca/publicati...9-13-2-eng.pdf
para 4.
(d) Low muzzle velocity/energy guns – Any barrelled weapon that is not designed or adapted to discharge
projectiles at a muzzle velocity exceeding 152.4 metres per second (500 feet per second) and at a muzzle
energy exceeding 5.7 Joules, or to discharge projectiles that are designed or adapted to attain a velocity
exceeding 152.4 metres per second (500 feet per second) and an energy exceeding 5.7 Joules.
Both thresholds
of 152.4 mps and 5.7 Joules must be exceeded for the firearm to be considered “controlled”. This requirement
exempts firearms that fire below the threshold velocity with a standard projectile, but exceed the threshold
velocity when fired with a high-velocity projectile
take page 8 of the memo for reference and you should be fine if they give you hassle. I'm only speaking from speculation though, not experience.