4d reamers in Montana rents quality, sharp reamers.
I had a customer carry in a barreled action in one hand and a barrel blank and rented reamer in the other. I guess he thought I'd do the work while he waited. I examined the reamer, which had a removable pilot, and it took great effort to turn the pilot with my fingers (it should spin freely). I figured it was packed up with chips, so, I removed the pilot to clear the obstructing chips. It wasn't chips, it was a pilot that was egg shaped! It should have been caught when the tool was returned from the previous renter! I'd call that "poor or non-exisistent inspection". I read around on several of these forums. I've caught, more than once over a few years, some bragging they'd "fixed" or set head space on a short chambered barrel by "renting a reamer and chucking it in their 1/2" B&D" to do the work. How many others have followed these posters lead and done the same? Crap like this doesn't inspire confidence. Take a specialized machine job to a machine shop, if the shop doesn't have the specialized tooling to do the job, they buy it! That tooling becomes part of the cost the customer pays to have the job done. If you want to play with wildcat cartridges be prepared to buy reamers. The original question from the OP was, "looking for a gunsmith who has a 6.5 STW reamer" and take your chances that the reamer he has is to the specs you want.
"Shoots real good!": definition; it didn't blow-up in my face. Not everything can be fixed on an internet forum!