I have a rule of thumb when desigining/building anything to do with airsoft "unless your willing to take a hit with whatever your building point blank, go back to the drawing board" I won't decry your recent efforts, seeing as others have quite obviously pointed it out already. I am pleased with the fact that your using your mind and talents to simply try ( most never do) but please rember that you have to keep your safety and the safety of others in the fore front of everything you do. When desiging items you must always ask yourself " what would be the absolute worst thing that could happen" and assume the something twice as bad as that is going to happen. I won't lie most times this will lengthen the whole process considerably, however, your finished product will be far better than orginal concept. It will stand the test of time, you will have something to be proud of, something people will use, and most importantly something that can be used but will not seriously hurt anyone. The last one is the most important. Good luck with future projects, IMHO the above design has to go back to the drawing board ASAP, perhaps with this post in mind you will be able to build what you like in a more " user/target" friendly version
"Pain is just a symptom of weakness leaving the body"