ACTUALLY...
I found this in the Five on Fridays, from WAY back, but haven't had the chance to add to the FAQ.
According to the devs in that FoF - bow and saw runic properties can STACK if rolled twice. In other words, you can roll a property twice and they add, still counting as two properties.
However, I also think that later they changed it to where they didn't stack, but gave fletching runics extended ranges greater than the others, since you can't craft 1-handed bows (and therefore are missing bonuses from the shield slot).
Either way, it is quite possible to have a 141 luck runic-crafted bow