Here's the relevant areas.
Section 25
A person may transfer ammunition that is not prohibited ammunition to an individual only if the individual
(a) until January 1, 2001, holds a licence authorizing him or her to possess firearms or a prescribed document; or
(b) after January 1, 2001, holds a licence authorizing him or her to possess firearms.
Unauthorized possession of ammunition
Section 108.
Every business commits an offence that possesses ammunition, unless the business holds a licence under which it may possess ammunition.
**Note that it says business.**
So what are we left with? I can't transfer (give/loan/sell) you ammunition if you don't have a PAL because it puts ME at risk of prosecution. Which means you can't buy it. There is nothing in the firearms act that I can find that says you need a license to possess ammunition as an individual. Even in the Section 4 (Purpose) it says the act is to
"to provide, ... for the issuance of
(i) licences, registration certificates and authorizations under which persons may possess firearms in circumstances that would otherwise constitute an offence under subsection 91(1), 92(1), 93(1) or 95(1) of the Criminal Code,
Note that there's no reference to ammunition in the above, Subsection II deals with prohibited ammunition (whatever that would consist of)...
I'm not a lawyer, but according to this I'd say you're good to have it, but it's illegal for someone to sell it to you. Roll your own, and if your firearm is a prescribed antique and you SHOULD be immune to prosecution. Not to say a cop won't charge you anyway depending on your area. Probably easiest to get your PAL just in case.
Here's the Act so you can do your own research.
http://laws.justice.gc.ca/en/ShowFullDoc/cs/f-11.6///en