True enough, Bjorn...but length is only one way...too long means they'd be "weak". So to stiffen spine you can shim out side plate for the same effect, right... :)I used layers of elect. tape till I figured which way I needed to go and then started cutting...
If ya know how much center cut there is on the Massie, or lack of it, that would help you know if its a lot, (like BW/Morrison) you will need way stiffer'n the draw weight might indicate...
If it's less than center or AMO, 1/8" shy, then you can figure on em requiring closer to what your draw weight might suggest... fwiw.