Paintball markers are permitted only in checked baggage.

Paintball Guns or Markers;
* No CO2 cartridges
* Must be clean or new
* Disconnect any battery sources for defogger or fans
* Any tanks must be drained with the valve if equipped secured in the open
position or removed
* To be placed in gun case, or comparable checked baggage for protection
* Must be approved by a WestJet agent

As per WestJet.