I'm guessing 20" without flutes would be pretty close to 21" with flutes. We're talking around 6 oz. I'm not sure the weight per inch of that heavy barrel, but would think I'm pretty close.
If I wasn't going to flute, I'd probably go 20". That 24" barrel is way too heavy. If you can find out what 3" or 4" of that barrel weighs, please let us know.
DF
