There are no limits here, just the most powerful power airsoft guns available. These guns are limited, advanced, custom built and available nowhere elsewhere. These specially tuned 500+ FPS (with 0.20 gram BBs) guns require advanced upgrades and absolutely quality parts, fine tuning done by a highly skilled airsoft technician, and a lot of quality control testing to be made possible. The amount of work to get these guns performing to this degree is different, with some guns requiring fewer upgrades to break the threshold of 500 fps such as the spring sniper rifles. More complex airsoft electric guns will require an overhaul of almost every internal part to ensure its performance and longevity.