Well, I have tried both the cartridges and the bulk, and the problem appears to be the same with both. When I first charge the tube I don't hear anything. But when I cock the bolt back I hear a rush of gas until I close the bolt. After that I don't hear anything.
I just took it outside and charged it up on the bulk rig. I shut off the valve to the bulk tank, and then I cocked it. When I fired it, nothing happend--like it was out of gas, but it is charged up because the tube and the bulk fitting are cold as hell and sweating. Outside, where I don't get any sound interference from fans or AC, I can hear the gas leaking out through the barrel. You can distinctly hear the gas escaping but you can't feel it. It appears now that the valve isn't working at all. I am fairly certain it is not leaking at the endcap or bulk fitting. I put some silicon grease on the o-rings on the endcap as well as the bulk fitting to make sure they were sealing good.
And now, I just went back to see if the pressure had bled down. It had, so I was able to disconnect the bulk fitting and tank. I don't hear the CO2 leaking as I put my ear up to the end of the barrel. So, I guess it is the valve?
Bevo66