Actually a dumb question, but here goes.. looking to build a 10/22 and am looking for a barrel that will shoot it all. Can i shoot reg ammo through 1/18 twist for hyper velocity or what ? Green mountain has 1 for hv now and am interested in shooting both, do i have to make 2 guns?

Anyone?

You might be fine with just about any barrel unless you want to shoot stingers through it.  

*I may be wrong, but I have a Adams and Bennet (basically a GM with a different name on it) and shoot just about anything through it.

My (and most, pretty sure) GM will allow anything from subsonic to high velocity to go through the tube.  
It has a "bentz" chamber...which is basically a match chamber with slightly looser tolerances, so it'll function better in a semi-auto.

Stingers and other hyper velocity ammo is not good for these...as the bullet itself is too long.  
I think it's more of a chamber issue, than a twist rate issue.

Please correct me if I'm wrong, I'm dead tired...so I could be wayyyy off on all this.  

The hyper velocity stuff is fine for the factory ruger bbl.  It wasnt any more accurate than high velocity rounds though, at least in my factory bbl.  YMMV