Welcome to RFC! Others will weigh in, but it is my understanding that the velocitor is the same length as the standard Long rifle, so it would work fine in your barrel. It is not advised to used the cci "stinger" that comes in the blue box in your GM barrel though. Tighter chambers like the GM barrels have don't like em.
I use Velocitors on occasion for knocking over steel plates at 100yds. Definitely have more punch, and would probably make a great hunting round.
:Welcome:
By the way, since you are new here, be sure to check out the For sale forum. Dave still has some raffle tickets available for a 10/22T. Good cause and only 5 bucks for a set of chances.