I know my BC gap was .003" wider on the left than the right. I don't know if that could have caused an odd wear pattern on the front of the cylinder from more pressure and powder being forced out of one side than the other over thousands of rounds or not. Kind of sounds like your forcing cone was machined crooked like mine was for the pistol smith to say the barrel needs to be taken off and recut the forcing cone.
I wouldn't have noticed mine being crooked if it wasn't making that loud crack and all the noise come out the left side. I got checking things out pretty close trying to figure out the problem. Glad I got it taken care of early.