I remember reading an overview of the experiences gained in "The Secrets of the Houston Warehouse" by David Scott
https://precisionrifleblog.com/2013/...ifle-accuracy/
where Virgil King stated that for a 6ppc, the barrel "must be 21 3/4 inches long for maximum accuracy".

Since barrel length has everything to do with harmonics, and some of us use harmonic tuners just for that reason, it's not inconceivable that you hit upon a better harmonic than the factory length barrel by cutting and crowning your barrels. In the end, I am a firm believer that anything you do to improve your confidence in yourself or equipment is probably well worth the effort expended and will benefit and add to your shooting skills.


For entire article go here: http://www.angelfire.com/ma3/max357/houston.html


Edit: I just re-read the above full article and would like to correct the 21 3/4" reference. That length of barrel did not apply just to the 22PPC, it applied to all the calibers he tested, .22, 6mm, and 30 cal.
Every barrel he had made was cut to 21 3/4 inch and target crowned. Didn't matter what contour, it had to be 21 3/4 inch, and setting back a barrel to gain some life ruined the length requirement and would never shoot as well.