To fit a barrel blank to a rifle receiver you need a lathe. The lathe I use is an Atlas/Clausing Model 5914.
The barrel I am threading here is a Christensen Arms carbon fiber wrapped blank, .270 caliber with a 27″ over all length. Here you can see the muzzle set up in the chuck. Supported by card stock. The Christensen barrels only have 5/16″ of steel at the muzzle, the carbon fiber needs to be protected from being crushed or marred.
The barrel set up on the lathe for threading. Here, you can see the recoil lug and thread diameters have been already cut. I debur factory recoil lugs and they usually end up few thousands larger the thread major of the barrel.
Approximately thirty passes later of a few thousandths advancement each you have a barrel which will fit your receiver. The bolt will not close on a 700 at this point, the tennon is just about 0.020″ too long and there is no counter bore yet for the bolt nose.
Set up in the steady rest as below the thread tennon is cut to the correct length. That length depends on the thickness of the recoil lug being used as well as how much material was removed from the receiver when it was trued. Here you the barrel with the tennon cut to length and the counter bore completed.