This is the first lego gun I have made which can fit under a regular gun and fire grenades/rockets. The main thing the G1 fires is the X3 Mini-Rocket. The G1 can also fire the Y1 Shotgun Shell from the C3.1 video, making it useful for close-quarters. The G1 has a 45 foot range (when firing the X3 at an angle). It is also very powerful and fairly accurate. To load the G1, the launcher must be taken off of the gun, and the top opened, so that the rubberbands can be placed on the firing gear. Then, the top is replaced, and the whole launcher put back on the gun. To load, the X3 Mini-Rocket s simply slid down the hole in the front, and it 'locks' in place, because the rubberbands keep it from sliding out, which is very useful. To fire, the 'hair' trigger on the back is pushed down. The launcher can be easily removed because of how the top was designed, and can be put under any gun with 6x19 studs of free space underneath it or more. The launcher does not misfire, and will not fire accidently.
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For the G2, I intend to add many different new features, such as: the firing system will be semi-automatic, and will be able to hold up to 2-3 shots' worth of rubberbands, it will be shorter, and there will be a true trigger placed on it.