It is kind of a unique rifle, mine is fairly fun and I can cast five different bullets to get different power levels. Might be able to do patched round ball if you really wanted to try something different.
I DO NOT like the lack of technical info!!! But I'm overcoming that by making repairs. My 5k burst disk failed in the middle of the night, odd part is that the rifle only had about 2000 psi in the bottle when it failed. Captain Oring to the rescue with the Ninja Reg. reseal kit.
No more magic from the rifle, it's just a Ninja bottle regulator set for 3000 psi, not the magical, mystical system they make it out to be in the sales info. Need to figure out how the barrel threads into the "barrel nut" so I can take up a couple thousandths of space which should reduce the blast. Might just need a new oring too.