I'm thinking of a newer, better barrel for my old FP. My question to the experts is what length should I get? I'm leaning towards a 6mmPPC. The furthest I ever anticipate shooting is 'maybe' 300M and 99% of the time at 100M . So, would I benefit from a shorter stiffer barrel with possibly tamer harmonics so as to ease on some of the many variables with load development? Or will the shorter length kill my velocity and accuracy? In short, what length, twist rate and contour do the 'experts' with more experience than myself recommend for obtaining the best accuracy with the least effort? I want this to be a one time purchase as I'm not wealthy by any means. This will be strictly a bench rifle so weight isn't a factor.

I welcome any and all input and advice so feel free to school me and tell me what I should or shouldn't do.
Thanks