sonix w/o expansion chamber questions

[clueless]

got a sonix pro with expansion chanmber and one without.on a nice cool day such as today the sonixw/o the chamber busted balls in the chamber/hopper,while the other didnt.we were shooting about 270-280fps.

would an expansion chamber help this out or not?the one sonix was the only one giving us problems.

[Maj_Paint]

All the expansion chamber does is allow the liquid co2 to become a gas. That helps stabilize your shots, velocity-wise that is. It might be a problem with your bolt or possibly detents. I'd also check your barrel for junk.