The original Disc had a 24" barrel and used the orange round disc. The extreme has a 26" barrel and uses the red full plastic jacket. If pick a Knight I would go with the extreme, I really like the way the bolt loads and unloads the 209 Disc... but you are on the right track with the Triumph. I would wager the TC will shoot as good a 100 yard group as the Knight if not better and will be ten times easier to clean.