I have a 6mm, 1.25 " dia. Hart barrel, a multi-flat Bat action and a Shehane MBR Tracker stock that I intend to combine to build a 6mm BR bench gun. The barrel has a 1:8 twist and I will likely shoot 90 to 105 grain Bergers. The piece will be used for non-competitive 100 yd. bench rest shooting. Weight considerations aside, what is the optimum barrel length for such a combination.