What is the "best" spring for a Longshot cs-12

Hi everyone, 

I was wondering what is "best" spring for a longshot cs-12. When I mean best I the most power while considering ease of use.

For example, a 22 kg spring has so much power but even with reinforcement, it is incredibly hard to prime. A 7kg spring is easy to prime but, only shoots ~80 ft. I want to say that Oznerfnerd's (14 kg spring) is the best choice but I don't know if it's hard to prime. 

Thanks,

- jsharma17