Paintball guns are not "perfectly legal" in Canada. Trust me, I've fought Customs on this a time or 2 before. If it looks like a gun, hoses or not, they can and will classify it as a "replica", which means prohibited. I have fought them on appeal and lost more than I won.
You may have had some success selling to Canadians. But most Canadians have not had success. Why do you think there are no retailers in Canada? The paintball trick has been tried before and to no avail.
You may get lucky and get a CBSA agent who could care less, or you may get one that actually enforces their own published policies. Like any civil service, you take your chances.
Most gun parts are legal to import without a license. The CBSA has a watchlist of certain parts, like lower receivers, FA kits for AR's, etc.
Age verifier Northern Alberta
Democracy is two wolves and a sheep discussing what's for dinner.
Freedom is the wolves limping away while the sheep reloads.
Never confuse freedom with democracy.