all shafts bend. You want them too. If they dont, they will snap or stay bent. That is why spring stainless steel works so well for spears. The best shafts are just harder and denser spring steel but they still bend. Your loading problems will
not be solved by buying spring steel.
If i was you, i would release some air in the gun until you get your technique down. I can load pneumatics very well with super high pressure because im used to it over the years. You still need to buy a real shaft though because that shaft that came with the gun will rust anyways.
If you think 97cm gun is hard to load, try loading a 130cm
I never messed with power regulator. If you asked me, its a complete waste. Mine is rusted shut on full power.
I guess if you are shooting into rocks less power is good. I rather just sharpen it more
Mostly everyone cranks their gun up as much as they can handle for
MORE POWER! 
