To the OP:

Make sure the mainspring strain screw is tight. Some people back it off to get a lighter trigger pull. But that produces misfires, esp. with British ammo, which has harder "caps" (primers) than do US and Canadian loads.

Is .38 S&W ammo more common in Canada than in the USA? I know that Domion/CIL is out of business, but US ammo makers may ship some up there, as Canada used the round as a military load.