Will he answer the phone or return a phone call? That would be my first option from afar. I didn't have that option because my gunsmith wouldn't answer the phone or return a phone call during the last 8 months of my 2 1/2 year ordeal.
Three states away sounds relatively easy compared to one nation away. Me in Alaska. The gunsmith in the 48 states.
I feel your anguish. I was there one year ago. I finally called the manufacturer of my custom action, who was located relatively near the gunsmith, and asked if they had a FFL record of transferring my action to the gunsmith. They said yes, and then asked what was up, sensing that something was awry. I'd selected this smith, in part, because the action manufacturer had suggested him. After hearing what I'd been through, they agreed to try to mediate the mess on my behalf, and were able to retrieve my action and all of my build parts. It did cost me some extra money, but that was minor compared to the loss of all by build components, which I'd already resigned myself to.
Like I said, I understand the anxiety, having just been there - done that. After 2 1/2 years I was happy to simply retrieve all of my rifle parts and pieces. I should clarify that I'd provided my gunsmith with all of the build parts. There was no wait time for any of the parts. I'd basically given up on ever retrieving a completed rifle. I would have bailed as soon as the communications ceased if I'd been local to the gunsmith. It took me another 8 months to finally stumble into a solution. I never called the action manufacturer thinking they'd intercede on my behalf. I contacted them to obtain proof that they'd transferred my action to my gunsmith. I was preparing to pursue a formal legal remedy.
6 years? That's gotta be an all-time record. Something is seriously - VERY seriously - wrong with your gunsmith. Shy of lying on his deathbed, you should have received your rifle at least 3 years ago. No gunsmith in the world is worth a 3-year wait for a common custom rifle build. Let alone a 6 year wait. 6 years is 1/10 of some folks entire life. And 14% of an adult life, if one lives to be 60 years old. I see folks in the obituary in their 50s on a common basis.
You're for sure in a bad situation. If he'll talk with you on the phone, cry Uncle and tell him you simply want to retrieve ALL of your build parts and move on. If he won't talk over the phone, then it's even more dire since he's out of state. Think it over and choose the best option you can come up with. Doing nothing is getting you nowhere - at a snail's pace. How much worse could doing something be? Perhaps a road trip with a tape recorder running, along with a friend/witness.
I've never ID'd the smith that failed me on a public Forum. But I have not one good thing to say about him verbally.