BTW..... this thread (and many others if you can find the old threads....) alludes to "Bill Calfee's book" sometimes in a snide fashion.
Some feel that Bill Calfee is a good rimfire gunsmith.
I am one of these, and furthermore just flatout like the guy.
Others don't.
"The Book" as it useta' be referred to has come to fruition in the ensuing years, all 750+ pages of it, and of coure I, being me, have a copy and enjoy it.
But in any case Bill does use a 'hobb' to address the problem broached by the OP in this thread, and in his book he details it's use. Take it or leave it, I'm all done arguing with the sort of folks who drove Bill from this board, the throat on a Bill Calfee rifle is a work of art.
Fact.
And as my buddy Jesse sez..."Ya' Cain't Argue With The Facts" so I will state a fact from 'The Art Of Rimfire Accuracy' as I read it.
Bill Calfee essentially irons or peens his throats into shape using a hardened rod ground to mimic the contour of the bullet of choice. He's used many different methods of application but ONE method he writes of is to chuck the barrel in the lathe, spin it at about 40-80 rpms and use the hob to gently TAP-tap-tap-tap into the leade area.... followed by using lead laps and very fine compounds to polish the throats to shiney mirror-looking finish, hand fitting them to the shape desired. Then he sez it still takes a couple thousand rds in some cases to season in...
Worthy book in my opinion
Not A Fact
al