Here are some that you would have to cut down. Being the intended use of that gauge was for birds, generally all of them will have long barrels. Remember you can still get your Billy-bad-ass fantasy on by playing like the character Everett Hitch in Appaloosa. He carried a long barreled 10 gauge SxS. Might be a hard to find item, unless someone else thought it was a good idea and has since decided otherwise and wants their money back out of one.
Those guns are far too nice and expensive for me to ruin. I'm looking for something within the 500-600, maybe 700, dollar range. Besides, Zabala's don't like lead shot, I'll ruin the barrels with that stuff.
Why a double 10ga? Why not a double 12 ga? The 10 ga ammo is hard to find but the 12 gauge can be found anywhere from buckshot to birdshot to slugs. You can only kill something dead and cylinder bores limit the use to fairly close range. The 12 will do anything the 10 will do at cozy distances.