http://www.cbsa-asfc.gc.ca/publications/pub/bsf5044-eng.html#P012
what I dont know is if you pay the duty on the estimated value or what you pay, whic is in this case nothing, I'll find out at the border when I go in, not a big deal in any event...
The big issue is that, even though our govt lets us bring the ammo in (as they should), we aren't allowed to transport it ot the border ourselves, by the US govt. I don't think reloading components are so restricted but I'll find out, with companies like higgensons here in Canada it isn't worth risking a hassle to save a couple bucks.
from site above:
Ammunition
You may import authorized sporting and competitive ammunition and reloading components for your personal use.
Quantities that may be imported for personal use and not for sale without requiring an Explosives Importation Permit from Natural Resources Canada (NRCan) include:
small-arms, sporting ammunition, up to a maximum of 5,000 rounds;
primers, up to a quantity of 5,000;
empty primed cartridge cases, up to a quantity of 5,000; and
propellants, smokeless powder in containers not exceeding 4 kilograms and black powder in containers not exceeding 500 grams, up to a maximum total combined quantity of 8 kilograms, (17.66 pounds).
Consult with the Explosives Regulatory Division at NRCan to determine if the ammunition you wish to import is authorized and approved for importation and use in Canada. Note that tracer, armour-piercing and similar military cartridges are prohibited under Canadian law.
Within these limits, non-residents can import 200 rounds duty free for hunting purposes, or up to 1,500 rounds duty free for use at a recognized competition.
You can make arrangements to import larger quantities through a Canadian shooting association, committee or federation for team practice and competition at meets. For information on permits to import quantities of ammunition in excess of those mentioned above or for the purposes of sale, contact:
Explosives Regulatory Division
Natural Resources Canada
1431 Merivale Road
Ottawa ON K2E 1B9