I would be tempted to hack saw off a little at a time and then test for blast and loudness. 22" should be no problem but I might stop at 21". Leave a quarter inch or so extra for final finishing and crowning by a gun smith. I have been getting a recessed target crown put on my barrels and it seems to direct noise away from the shooter better than a flat conventional crown. Also a barrel mounted sling swivel lowers the rifles muzzle for shoulder carry if it doesn't already have one.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli