Your opening post says, "Looking for a gunsmith". Seems you weren't 'looking' or you have already looked as much as you are willing to. Metric threads aren't a problem for a real gunsmith, only for the newbe/wannabes. As for supplying the parts, well,,,, 'parts',,,, barrels, stocks and the like are today sold in quantity. There is no price break for the one at a time purchases on 95% of those things. And, as every custom has varying and different 'wants' it is all but impossible to buy 'quantity'. Buying 'quantity' ends up where the shop only will provide a particular style, a style you may not be interested in. Here I am thinking of companies like Gunwerks, where not every option you desire is to be had, and that's not to pick on companies like Gunwerks, I just used them as an example. And, they have their place in the custom rifle market. No price break means there is little or no profit for the gunsmith to supply the 'parts'. Would you, if you are business for profit, tie-up your dollars for a no profit deal? These days, many seem to want to treat every gunsmith as strictly a 'laborer' , to 'put their rifle together' for them. Assuming all there really is to it, is to cut/crown/thread/and chamber their barrel for them. As for the pre-fit and barrel nut, if you can change spark plugs,,,,,,,,,,,,,,, But that doesn't make you a mechanic, either. I see a huge difference between 'home builds' and builds done by true gunsmiths. To each his own! There is heirloom quality work, and then there is off the shelf/average work. I have had clients 'dump' parts on me to build their 'custom'. Many times 'parts' that would require lots of extra labor to make them work as they were not compatible to begin with.