RSOV retails more than just airsoft guns. They retail parts and accessories as well. You are more than perfectly welcome to purchase upgrade parts and gear and have it successfully imported.
Lets take an excerpt from the east coast airsoft website
EastCoastAirsoft prides itself on being one of the few retailers that ships to Canada. We very rarely have problems with Canadian shipping, but there is always a minute chance that your order will be seized and not returned. EastCoastAirsoft does not take responsibility for any lost, stolen, damaged, or seized packages.
Sure they have no issues shipping to Canada, how hard is it to give a box to the postal worker and pay the applicable fees? They can say and make up whatever they want but the fact of the matter is that airsoft is not available for civilian importation. Reread the above statement but instead of EastCoastAirsoft pretend it said EastCoastCocaine or EastCoastHeroin. Once they have your money they dont care.
Please review this link before asking any further questions.