2 liter chamber is safe?

[MrCrowley]

In northern climates like Canada ABS is more common than PVC because of the potential of frozen pipes. PVC will shatter but ABS is resillant to expansion loads. And can take shock loading better than PVC.
You wan't a big cannon please shy away from pvc. I'ts just not safe.

Its hard enough as it is to get PVC in Holland let alone ABS. The climate is different, to find ABS pressure rated is bloody hard but to find it in large diameters and with fittings is even harder to get. PVC is perfectly fine for huge cannons as long as its pressure rated,you stay below the pressure rating and it doesn't get knocked around too much. Pressure rated ABS would be more ideal,lighter, it tears and is more shock resilient but its still very difficult to find in large diameters and pressure rated.