Well, the plot thickens. Darn it. I set up my back stop & new Caldwell deluxe chronograph with IR LED's. Then proceeded to put the two Co2 cartridges in the 160 & screw down the cap to pierce outer cartridge, then cock the bolt to pierce inner one. Pulled trigger, cocked the bolt, pulled the trigger again & all the gas leaked out on it's own something isn't sealing between shots somewhere? It fired while it still had gas, but wouldn't hold it between shots. Sounded like it was leaking out the barrel, then out the exhaust port to breech as well??? I did weigh the rifles in a new Youtube video. It now weighs 6lbs, 4.4ozs, minus Co2.