Help with arrow selection

[rmekus]

I need to get some new arrows set-up for the new bow I am shooting and looking for some advice.
I am shooting a Bowtech Rpm360 set at 26.5 Draw length, and 66 pounds. I have been shooting GT Hunter Xt in 400 spine cut to 26.5 amo with 100 gr tips. I am thinking of giving the Black Eagle Rampages a try and am wondering if I should go 350 spine or stay with 400? The other arrows I am considering are the GT Kinetics or the Easton Axis however the same question applies to those as well. I am not yet building my own arrows so looking for a recipe to have the local pro shop build. Thanks in advance.

 

[OR Archer]

As long as you continue to use that same weight head you'll be just fine with a 400

 

[rmekus]

I am debating perhaps going to a 125gr head to boost TAW a bit. Would that require a change to 340-350 spine? I am still trying to get up to speed on the science of arrows.