ARES have come out with a Bolt Action CO2 Conversion Kit With a M130 spring for the ARES TX System sniper rifles such as the MS338 and the MS700. This component turns your spring cocking rifle into a CO2 powered sniper rifle. Please check local laws before installing this bolt as it may be illegal in some places. This bolt uses a 12g CO2 caplet that you install into the bolt. You pull the bolt out of the gun, open the cap to drop in the 12g CO2 caplet, then twist the lid to close and pierce the CO2 caplet. Reinstall the bolt and you are set to shoot over 100 shots with a single CO2 powerlet.
Installation of this item requires basic gunsmithing knowledge. If you have never performed an upgrade yourself, consider having us do it for you properly to risk damaging your rifle.