Talking about Co2, I had only but bad experience when using them with my WE M4/M16A3 Co2 ready. The blowback was crisper, but on chrono I was falling from 560fps on propane to a max of 440fps. I never gained any fps with Co2.
And why would it break if it's suppose to be Co2 capable? The internal is all metal/steel, I'm pretty sure it can take it?
I would love a longuer barrel but I don't know anyone longuer then the 505 Ra-Tec and WE one
And I read something pretty weird and sure it is misinformation but TSC claim that their SCAR adjustable rod can go from 200 to 600fps. I know it's bullshit since I never saw anyone with a 600fps SCAR. But still maybe it can go over 500fps?