I just bought a Barnett predator crossbow it came with 4 bolts 22"long but they don't have a size on them. What size bolt would this bow shoot if I buy a brand other than Barnet? Would I be able to use Rage two blade points in a crossbow?
I would not use the Rage in that bow. It is a very dangerous situation. The blades will deploy as soon as the trigger breaks,(not every time, but if they do) if they hit the foot stirrup you will most likley shatter your arrow, causing a partial dry fire.
Lots of good arrows out there for that bow. Just make sure you pay attention to the minimum weight. Gold Tip Laser II Kinetic would be my first choice as they will bring the speed down some and add kinetic energy. The Barnett 515 grain arrows would probably be OK too. The Victory with the heavy brass insert should be a good one too. In any case, I would find ones with a brass insert to get the weight forward.
I don't shoot a crossbow , but on the rages, you can still use them , I always use a small dental rubberband on my rage blades out of a compound , it keeps the blades closed , and still opens 100% of the time.
Sometimes that info is also available on the manufacturers' website. Some of the better ones even have manuals that you can download. It is very important to shoot enough weight to avoid possibly damaging a bow.