For this gun, you can use either grey, red and yellow rods to shoot with. For yellow rods I recommend that you add a connector to the end of it as for some reason it goes further. This gun was designed based on two previous models I made. One fired well and the other looked good so I put the barrel of the one that shot well with the slide of the one that looked good and added some more pieces. I then made made the handle and trigger myself. If the trigger does not work then you just need to adjust the tightness of the elastic bands. This gun is very accurate and I strongly suggest that you fire at knex targets like my duck shoot not people. I am not responsible for any injuries.