Which parts specifically? I haven't had an issue finding a number of Magpul parts over the last 6 months.
Have you tried Arsenalforce.ca - aggregate price/availability search specifically for firearms, ammunition and accessories in Canada.
Not perfect, but it's helped me find a number of things.
I've purchased Magpul items from Tenda, Marstar and RDSC most recently.
Footnote about Hero Outdoors. If Hero Outdoors actually has something physically in stock, they're fine. Unfortunately they also list some things as being "in stock" when they actually have them shipped from the states when ordered.
Best thing to do with them is call them and ask them if something is in stock as if you're going to the store that day. If they say they can't give it to you that day, don't order online.
Anytime they actually have something physically on site, they ship reliably and quickly. If it's not onsite and they have to get it from one of their US partners, it can take weeks or months longer than expected (or not arrive at all).
