The whole point of the level 10 is that it's a two speed bolt which goes slow in the first stage and fast in the second. This allows you to have the best of both worlds, be soft on paint yet not sacrifice ROF.
you need to be able to fire at 280-300 or the marker isnt going to get you very far.
1. Slowing down my velocity.
the pressure is regulated before it goes into the dump chamber so all the last thing you want is to starve the valve of air.
2. Turning down my output pressure from my tank.
OR you could just do what I said and use the biggest carrier that doesnt leak. Using a tighter carrier means you need more pressure to get past the friction which inturn means that by the time you do, the bolt is flying faster than it should be in the first stage.
3. Putting on yet a smaller carrier which in turn puts more friction on the rod inside the bolt?
Do that to any other type of marker, it usually works, dont worry- it's safe.;)
4. Smash it against the floor and jump on it a few times.