Britain and Australia are the other countries mentioned as examples. In both these countries, firearms were confiscated and destroyed, with substantial compensation being paid.
In the UK, the total was hidden behind the Official Secrets Act; in Australia, a surtax was added to the health care tax. Many millions were paid out in compensation.
If you assume that there are over a million restricted firearms and unregistered "assault rifles" in Canada, a ball park number for the cost of compensation can be estimated. Total would be at least 500 million, possibly a billion or more. Now Justin has never seen someone else's dollar that he is unwilling to spend, but that is a lot of money when a government is running deficits and heading into an election.
Far cheaper to just prohibit and grandfather. Its worked for them in the past. Delays the trip to the smelter, but with time and age, its inevitable.