SpudFiles

If your gonna be using something that powerful you might want to build a pressure net around it, make an outer chamber and pressurize it. This will keep the main chamber from overpressurizing by reducing the "Net force" on the chamber walls.

That is exactly what I was planning on doing Atlantis, I want to use SCH 160 Stainless steel for the chamber, and most likely SCH 40 for the outside pressure chamber. BLB, my goal is to acquire higher velocitys and I will have to look into helium-fuel-oxygen mixtures, I never though of that.

Also what does "microrant: Energy" mean. Im not familiar.

In physics, power is work (applied energy) devided by time, with energy being a measure of ability to do work. Roughly. Sorry I botched a semantic detail.

Essentialy, a engein can be powerfull, as it runs for an extended period.
While a spudgun does have a barrel dwell time during it does work, we don't really care about this, so so it's probably more suitable to describe it as 'energetic'.

As an example of the difference between these two terms as used in physics:
A 5' barrel on a combustion or a 2' barrel on a pneumatic give the same muzzle energy, but because the combustion takes longer to accelerate the projectile, it is less powerfull.