As usual, not much left to be said after Dave explains something. But I would add just 1 bit of fact, and 1 bit of subjective experience:

I got the feeling that maybe you thought a lighter arrow would retain more of it’s energy / momentum down range. This is not the case. A heavy arrow will leave the bow at a slower speed than a light arrow. But at some point down range, the heavy arrow will be traveling faster than a light arrow.

What this means is that at some hypothetical distance, lets say something over 75 yds, the heavy arrow will get there first!

My little bit of subjective experience is that if I use too much weight my accuracy goes way down. I attribute this to bad form (it’s all I got!).

What I think happens is that with the heavier arrows, it takes longer for the arrows to clear the bow. Additionally, the wight of the arrow becomes a significant percentage of the weight of the bow. This means that I have more time to flub the shot, and how I hold the bow is more critical.

I haven’t put numbers to it yet, but I have found that I can shoot a heavier arrow out of a heavier bow better than out of a lighter bow. even though the arrow tunes just as well and flies just as fast out of each bow.

So where I have settled out as far as heavy arrows goes is this. Shoot as heavy a FOC arrow as you can that:

-Can be shot at least 160 fps

-Doesn’t “seem” like it weights a lot compared to the bow.

Or, an even more woo woo way of saying it is that I don’t like to shoot an arrow so heavy that the bow seems to struggle to cast it.

To sum it up, I think I shoot about 12 grains/inch, and try to put as much as I can up front.