What kind of silhouette shooting are you gonna do? In IHMSA, the 10" barrel is more versatile, as the maximum barrel length for a production gun is 10" (10 3/4 actually). A 12" doesn't gain you much velocity, and some folks swear that the longer the barrel, the more chance of your movement effecting bullet flight! In the standing divisions I have seen this to be possible.
The G2 and older Contenders use the same barrels. E-bay and Gunbroker have lots of used TC barrels, but getting a good deal may take some patience. There are a few 10" .22 barrels on both our new and old TC classifieds. Eds TC's has about anything you need, but you need patience and persistance to get ahold of him. Also, the guys in your silhouette club may have extras laying around. Good luck!