Yea. The pin idea I understand but it might fall out or break the way I'd install it. But I also have a few mods on my gun that will make it very difficult to take apart the gun and then the gearbox. I think he meant that I take a pin (made of metal), I'm not sure what kind though, and then hammer it into the side of the gun to prevent the selector from rotating down to the full auto position. This is definitely easy enough and I think it would work fine, but is there a possibilty of damaging something inside the gun when I hammer the pin in? If this doesn't work out though, what do I have to do to modify the gearbox? So far I've done everything to my gun EXCEPT touch the gearbox.(I don't really know my way around the internals of it) Oh yea, this gun isn't even close to the 500 FPS limit. I'm pretty sure it doesn't even reach the 400 FPS mark.