Try soaking your breech plug for about 30 min. Then take a small drill bit just big enough to fit in the hole and turn it back and forth with your fingers (DON't use a drill). That wil clean any carbon build up in the plug.
I had a left hand semi auto. I liked it, never had a bit of trouble with it. I shot every thing from light trap loads to 3in mag duck loads. They all shot the same. For the money it was a very good gun.