[img]http://www.spudtech.com/sp9004c.jpg[/img]
[url]http://www.spudtech.com[/url]

Cool site.  Mine has interchangeable barrels, I have one with an A1 bird cage flash hider, another with a version of the Bushy Y-comp break and a shorty barrel with a Phantom style suppressor that has a twist similar to the vortex.  I have been thinking of a method to rifle a barrel but have not tried anything as of yet.  I just built my friend one exactly like mine and we got it to shoot about 170 yards with a 36" barrel and aquanet.  The riffling on the barrel on the web site looksa bit too fast for a potato. I would think something in the neighborhood of 1:40-45 inches would be OK.