If the guy you know is competent and can use his lathe to turn it down, and it will fit through his spindle, then yes, it can be done on a lathe.
If it won't fit through his spindle (too large of a barrel diameter) then the barrel will have to be removed and a large lathe will have to be used and put between centers.
My lathe, despite being only a 7x12 bed will turn barrels up to a hair over .750" in diameter with the receiver attached through the spindle allowing me a lot more versatility.
Since I have purchased my lathe, I have threaded nearly every barrel that I own.
While your friend has it chucked up and turned down in his lathe, why not ask him if he can single point cut the threads? That will be a lot more precise than trying to use a hand die.
And just to mention, would allow you to use the correct 1/2-28 thread pitch that 22's should be in the first place because I think you're going down the wrong rabbit hole trying to use a 14-1 on it.
I get it that you already own the 14-1 die set and yes it will work but you'll be painting yourself in a corner by doing so, and this is probably one of the few times when I'll say that a job worth doing, is worth doing right the first time.
Nevertheless, here are the major and minor numbers you'll need to know for the 14-1 if you go that route. Scroll down until you find the 14-1 column
https://www.newmantools.com/tech/threadmf.htm