A few years ago, I acquired a l/h 12 ga. trade gun. This year was its maiden run for me. I had no problems with it. Like has been said, you should be looking down the barrel, not at the lock. I would have said sights, but since it has none, I said barrel.
A bonus for me was that since I carry my pouch and horn on my left side, it made priming the lock quite easy.
Aside: I forgot to put my primer in my pouch so I had to prime with my main horn. I was using up some Fg powder and the gun went off just as fast as I imagine it would have with Ffffg.