Smallest barrel to accept 5/8x24 threads w/out shoulder…

[ropeup79]

Main problem is a custom contour can take a real long time if you have to order vs purchasing an on the shelf blank. Otherwise I’d have all custom contours.

That makes sense. I’m still not sure why people would rather use a adapter and chance tolerance stacking instead of a threaded collar to shoulder against?

 

[MuleyFever]

Get the contour you want and have the end flared to .75". That's what I have done in my last 2.

 

[Kimber7man]

a 3b will be fine at 22"
a Bartlein 3 will be .725 at somewhere between 19" and 20" depending on how much shank your gunsmith removes.