Any gun company makes errors - there isn't much quality control in the industry. (In manufacturing, you have to focus on perfecting process, rather than units, and I think, either as a result of the "craftsman" tradition in the gun industry, or because the profit margins are too low, process never seems to be perfected.)
EG, I have had custom guns, which couldn't fire at all, I've had a batch of Virgil Tripp mags which couldn't be loaded (wrong springs in them), I've had brand new guns which wouldn't run, etc, etc.