I`ve got this answer from the MNR.
1. It is legal to target shoot on Crown land without a hunting licence. Of course the officer will have to believe that you are not hunting. I would suggest you plink as close to home as possible.
2. Section 109 of the Fish and Wildlife Conservation Act, states that: In a prosecution under this Act in respect of hunting or trapping, (a) proof that a person possessed, in an area usually inhabited by wildlife, a firearm, trap, decoy or other hunting or trapping device, a ferret or a specially protected raptor or other bird of prey, is proof, in the absence of evidence to the contrary, that the person was hunting or trapping, as the case may be….
In other words, the onus is upon you to prove that you were NOT hunting. The CO or PO would ask why you have firearms and it will be officer discretion. You likely would get asked for a hunting licence and why you have firearms. Refer to '2' above.
3. Check the 2008 Hunting Regulations Summary. They are available at no charge at most tackle shops and some Canadian Tire stores or check online at
http://www.mnr.gov.on.ca
If you still feel unsure about going target practising you might want to call you closest MNR office and advise a CO where and when you'll be out plinking.