Good question...but tuff! I'm gonna start off with four and whittle it down.
1- 10" 22lr- Hard not to start here...all that cheap shootin'...accuracy galore.
2- 10" .218Bee- May not be a popular choice...but I love mine. Your 10" .223/.222 will make more noise and fire but I'll bet my Bee will smack'em just as hard. Accurate too...New powder and bullets have given it new life.
3- 10" 30Herrett- You gotta dance with the one that brung ya. It wasn't quite my first barrel, but it was close. Gotten away from it a few times...but keep goin' back. 357Herret would be listed too if it wasn't fer #4.
4- 10" 357Max- My 10" Heavy Hitter with a little politeness. 45Colt used to be close here, but moved it up to the 14" group. Sorry guys, 44Mag was just never close here for me.
Well, I'm gonna have to think on it a little to do any whittlin'
Walt