Well I have a 311 here that dates back to 1953. I've been shooting it since 1984 and trust me, I shoot alot more than a box ot two a year. Did have to replace the firing pin spings a few years back, man was that a learning experience. I've had well over a dozen 311's and wish I had everyone of them back. That being said not all B's will swap with 311's and your's won't. The 311 has a single extractor that works both barrels with the BE's have dedicated extractors. From the looks of it you have a firing pin issue of some kind on that left side as well. Best place to find parts that I have found is numrich. At the very least it will get you a schematic.
John A. Monroe, Never Forgive, Never Forget, Blood Pays Blood