A matched bolt is a better term, IMO. Good barrel finishers will take the barrel they are sending to you and go through a selection of bolts to find one that mates with your barrel extension in a way that will keep you within headspace spec for a reasonably long time as the throat erodes. I've had White Oak Armament and Satern do this. In a similar vein, for Grendel, Compass Lake Engineering will check headspace with a bolt you send them to make sure whatever barrel extension they put on your barrel does the same. I would not expect any measurable difference in accuracy. It's just a way to avoid the need for headspace gauges and have some assurance of a longer barrel life. I'm sure many other finishers offer equivalent services.
Not too many shops both manufacture and finish blanks. Krieger and Lilja come to mind.
For the best chance at the best accuracy, cut rifled blanks are the top of the heap.
Many people consider Krieger and Bartlein (both cut-rifled) to be the top barrel blank manufacturers. Many other good ones exist like Lilja, Shilen, Douglas, Wilson Arms, etc. (all button-rifled). Step 1 is to figure out what barrel blank you want. Step 2 is to figure out who you want to finish the blank. Step 3 is the hardest: Figuring out who will deliver your finished barrel in a reasonable amount of time.
Not too many shops both manufacture and finish blanks. Krieger and Lilja come to mind.
For the best chance at the best accuracy, cut rifled blanks are the top of the heap.
Many people consider Krieger and Bartlein (both cut-rifled) to be the top barrel blank manufacturers. Many other good ones exist like Lilja, Shilen, Douglas, Wilson Arms, etc. (all button-rifled). Step 1 is to figure out what barrel blank you want. Step 2 is to figure out who you want to finish the blank. Step 3 is the hardest: Figuring out who will deliver your finished barrel in a reasonable amount of time.