Originally Posted by brucev

The following is my opinion and only my opinion. I would suggest that you begin with a thorough cleaning of the throat, cylinder, etc. Purchase and use a Lewis Lead Remover as it will do this job completely

Do check end shake and head space before doing any work that is permanent. If end shake needs attention, deal with that using end shake washers (Brownells). If head space is a problem, I don't know what to tell you as I have no idea how to fix it.

Look at the throat. It appears there are machining marks present. If this is the case, you might first want to contact S&W and request that they correct this. Your revolver has a life-time warranty. As this would be a manufacturing issue, it would certainly be something that S&W would deal with. They might simply clean up the throat. Or, they might fit a new barrel. Bring to their attention the current barrel/cylinder gap of .007 inches and the lead spitting.

If you decide you want to proceed with chamferring the forcing cone, it would be wise to consider sending it to an experienced gunsmith/repair facility. You might get it right first time out the door. You might not. But an experienced gunsmith who has previously dealt with chamferring forcing cones and who has the equipment on hand would likely produce better results. Given the cost of the tool required, etc., you would likely come out with less expense. HTH. Sincerely. brucev.