Hey, well today i just figured out how to do this and i'll tell you right now. this is the Most entertaining Semi auto-matic airsoft gun you'll EVER make in your entire life, AND it's Really cheap and will cost you about 2 to 4 dollars :P so besides all this . lets get sarted, first you need to purchase a cap gun, anything that looks like mine really, it needs to fit 6mm bb's in the chamber, or clip, or what ever you prefer to call it, either way they need to fit, so check before you buy one, and just go to the dollar store to find one, they're very cheap, oh and mine is already done in this picture. so this is basicly what it should look like when your done, but for now. lets just say it's a cap gun.
Step 1: The Rig
ok first you need, the orange part, needs to get cut open, cut it really wide like mine so the bb's just shoot right threw, but don't get too carried away or it will snap, we don't want that, so just take a knife like so. and twist it in one direction only, twisting left and right will only uneven the barrel making it and unaccurate and messy. sorry for bad quality.
Step 2: The Bb's
ok, so after your done that your pretty much done. just load some bb's in to this part of the magazine ( clip ), and then jam them in there nice and tight, but not too tight, because then the bb's will not shoot properly. so just give them a nice little poke or two with a pencil to make sure they stay in without falling. don't buy the dollar store one's either.. they suck, buy some 20g airsoft bb's if you can :P but they're probably the best. in my opinion.
Step 3: The Caps
now put your caps in the back.
Step 4: The Shooting
now just close the gun and pull the trigger, like i said in the start, it's semi auto. so don't be shy to just scare your friends with it. it's practically harmless. but don't aim for the eye's and be extra care full please, shoot at your own risk.
Step 5: Some Suggestions
well, i painted the tip of my gun, the orange piece to match the rest. so i painted it black. then i made a handy tool to get the bb's out from the clip when they are stuck. so just take a bobbing pin and cut off one end. it should be small enough to make it through the back. so these will help you. except the paint job. it's just cool.