To add to the conversation.....
I know of a Winchester Model 21 that was passed around to several well-known gunsmiths (who do wonderful work) over a period of several years to fix what was thought to be a basic repair issue. But after each of the well-known gunsmiths worked on it, there were continuing issues with the M21 that didn't get "fixed" to the owner's complete satisfaction, so the owner sent the M21 to the "factory" to have the factory work on it. Certainly the factory would resolve all issues and problems. But the factory wasn't able to do any better to straighten things out than the prior individual gunsmiths that had worked on it. Then the owner was told, "If you want the M21 fixed correctly and stop the aggravation once and for all, you need to take it to Gunter Pfrommer....he will fix it, and you will not have any more problems." I was told Gunter identified the issues with the M21 as soon as he inspected the shotgun....and Gunter did the repairs. The owner has never had another issue with that M21's performance.
Frankly, when it comes to repairs...especially complex repairs...I want Gunter Pfrommer or someone with similar training and skills working on my firearms. The factory may make them, but it doesn't mean they're the best to fix them when there is a problem...or restore them.
Many, many smiths fix the symptom. Very few have the knowledge and take the time to discern the originating problem first, fix that and then fix the downstream issues.
