A workable job can be done with a hacksaw,a file,a square,and a few roundhead brass screws and some abrasive.,since you aren't treading it.
My point: I use an old WW2 vintage South Bend Heavy 10.
It has approx. 1 3/8 hole through the spindle. We have what is called a "spider" which provides a tool to center the far end of a workpiece in the spindle.A four jaw chuck provides for centering on the working end of the spindle.
We use dial indicators on both ends to get everything running true and centered before the cuts. That's just workmanship.Even if its just a cut and crown job,you want everything as true as possible.
Your receiever may not permit the barrel to fit through the spindle to allow the muzzle to be worked on.
Many smiths have smaller lathes that lack the large through hole.
So its less easy.
It may mean pulling the barrel out.IIRC,Remington at least was LocTiting the barrels in.The separate recoil lug must be indexed on re-assembly.
Time is money.What do you pay any other trade,flat rate?
The barrel vise needs a split bushing to fit your barrel.The smith may have one.He may have to make one. 20 minutes?
Setting up in the barrel vise and pulling the barrel? Its sort of a three handed job,but if it goes real easy,10 or 15 minutes?
Band or hacksaw? or parting tool? A little time.Somebody buys the saw blade.
I usually use a pin gage from a pin gage set(maybe $100) and a $140 dial indicator ,or two,to center up.I may have to change chucks,and set up the spider.So,15,maybe 20 minutes.Everything has to be clean,chipfree when you change chucks,etc.
Now,actual cut time? Set up a facing tool and face? One minute. A little chamfer,corner break,maybe some sand cloth,three minutes.
If I had to thread? I could putz around 20 minutes or half an hour to get my toolsharp and set right,set the gearbox,the compound,and just go easy,take my cuts,check my size,and check the fit.
Now,clean the oil and chips ,and re-install the barrel and torque it up.Your Rem has a washer for a recoil lug.Something else to get indexed right.
All along the way,care must be taken to not make a mark or scratch.
Taxes,bills,rent,the ffl,etc have to be paid.
Time its done ,of your $100 the smith might get enough for his wallet to buy a lousy bucket of the Colonel's chicken and a six pack of cheap beer.
(He probably would just give you raised eyebrows and a crusty look if you suggested he eats the Col's chicken.He probably does drink cheap beer)