SmallCaliberCentral

Which is a better barel length? 21 or 24in?

yes

Depends on application. For off the bench or a shooting platform the 24" for it's ability to ride the bags a little better with the extra weight. Out in the field under woodsy type conditions the 21" will swing nicer & be less prone to hang up on under brush. Both will work nicely in reversed applications tho. I doubt you will be disappointed either way.

What Glen said. However, if noise and muzzle blast is an issue, in my experience the little hammer-forged C-Z American barrels are downright annoying in any round bigger than the Hornet. Am much happier after switching to the 24" Varmint. And, a longer, heavier barrel will arguably prove more accurate with more fps, and it takes longer to heat up and start stringing shots.