First, liquid co2 will never harm your gun. If the "snow" and cold barrel are no big deal, then the anti-siphon is a waste of money.
Here is a picture of my blowback with the barrel TOTALLY FROZEN OVER:
Still worked absolutely perfect.
The issue with your gun is the TANK ANGLE. Your tank is probobly parrallel to the barrel of your gun. This means that the liquid is entering your gun, and flashing when fired.
To fix that, buy a $5 adapter at your local paintball field so your tank will sit at more of an angle. that will keep the liquid at the bottom of your tank, instead of in your gun.
nick