But that's just to cycle the bolt and recock. It's still putting 300-400psi behind the ball to actually chuck it down the barrel. But unless you're using really cruddy paint, barrel bursts due to firing pressure are a lot less common than chops, so a lower bolt pressure should eliminate the majority of breakages. Hence why Lvl 10 Mags don't break a lot of paint, even though they operate at relatively high firing pressure.