Nitroassasin came over last night with his high end chronograph to test my tank's airsoft guns. I've started to use prometheus (6.03 inner barrels (before I was using madbull 6.03mm inner barrels). we were testing both 0.20g and 0.12g bbs. We were getting values as hight as 199fps for the 0.20g bbs and 238fps for the 0.12g bbs. Before, to get an idea of a gun's power I would use what I call "the cardboard box test" where I would see if the gun I put together could penetrate it I already knew which of my tanks had powerful guns. I've tried a few new techniques over the last week which has worked on increasing the probability that the gun will fire hard (upgrading an airsoft gun is as much of an art form as it is science. I think at this power level we will be able to fire and break paintballs at 50+ feet. I think I've even discovered how to make the longer barrel tanks work well with minimal loss if power ( the shorter the inner barrel (minimum length I think would be around 7cms) the more power you will get) This was tested on my Jadgtiger where my inner barrel is about 9cm long and my outer barrel is close to 30cm. The trick is to have a thin brass sleeve the fits just inside the outer barrel but also allows the inner barrel to slide in (outer diameter of the inner barrel is 11/32") I am going to try this technique on my tiger and kingtiger. Right now I am using inner barrels that are almost as long as the outer barrel.