There are no restrictions on using FMJ in Ontario.
Here is an answer from an Ontario CO on another Forum I frequent where you can ask the MNR questions regarding fishing and hunting:
http://fishingboard.thunderbayfishing.com/index.php?showtopic=3713
A. The main piece of legislation in Ontario that governs hunting is the Fish and Wildlife Conservation Act 1997. This Act has several regulations attached to it including one that deals specifically with hunting (Ontario Regulation 665/98).
Under this regulation, there are no restrictions on the type of centre fire bullet that can be used when hunting big game. The table on page 22 “Summary of Firearms Restrictions for Hunting in Ontario” of the 2008 Hunting Summary does a good job of explaining what type of firearm can be used during the various seasons for each type of game.
Ontario Regulation 665/98 can be found at:
www.e-laws.gov.on.ca/html/regs/english/elaws_regs_980665_e.htm
look under Section XI - HUNTING METHODS AND FIREARM RESTRICTIONS
Part III of the Criminal Code of Canada ( R.S., 1985, c. C-46 )deals with firearms, ammunition and other weapons. It can be found at:
www.laws.justice.gc.ca/en/C-46/
An associated regulation to the Criminal Code is Regulations Prescribing Certain Firearms and other Weapons, Components and Parts of Weapons, Accessories, Cartridge Magazines, Ammunition and Projectiles as Prohibited or Restricted (SOR/98-462.) The link to this regulation is:
www.laws.justice.gc.ca/en/showtdm/cr/SOR-98-462 Part 5 deals with prohibited ammunition
PART 5
PROHIBITED AMMUNITION
FORMER PROHIBITED WEAPONS ORDER, NO. 10
1. Any cartridge that is capable of being discharged from a commonly available semi-automatic handgun or revolver and that is manufactured or assembled with a projectile that is designed, manufactured or altered so as to be capable of penetrating body armour, including KTW, THV and 5.7 x 28 mm P-90 cartridges.
2. Any projectile that is designed, manufactured or altered to ignite on impact, where the projectile is designed for use in or in conjunction with a cartridge and does not exceed 15 mm in diameter.
3. Any projectile that is designed, manufactured or altered so as to explode on impact, where the projectile is designed for use in or in conjunction with a cartridge and does not exceed 15 mm in diameter.
4. Any cartridge that is capable of being discharged from a shotgun and that contains projectiles known as “fléchettes” or any similar projectiles.