Well, that was interesting,on page 3 of the bc hunting synopsis
Handgun – is a firearm that is designed,
altered or intended to be aimed and fired by
the action of one hand or that has a barrel less
than 305 mm (12 in.) in length.
The rossi has a 12 inch barrel so that's just long enough for hunting,shorter would make it a handgun in bc and i would say it's made to be fired with 2 hands as it has a forearm stock.
From page 9
Handguns
4It is illegal to hunt with a handgun in BC.
See page 3 for definition.
As for the co2,compressed gas just makes it classed as a firearm for hunting purposes.Yes you can hunt with a firearm in bc.
Firearm - includes a device that propels a
projectile by means of an explosion, compressed
gas or spring and includes a rifle,
shotgun, handgun, pellet gun, "BB" gun or spring
gun but does not include a bow.
NOTE
All this is BC provincial law and does not apply elsewhere.
http://www.env.gov.bc.ca/fw/wildlife/hunting/regulations/1214/docs/hunting_trapping_2012_2014.pdf