Interesting-
I took my first "test shafts" to the range Friday.
Shot from a 45 / 50# ish bow.
Shafts were 30" w/ 145 piles, spined 50,55,60,65,70,75#
Bow was never shot (by me), recommended brace around 5" (started around 4 1/2")
Tons of "shoot around" off the nuckle.
With low brace all were tail left (right hand shooting). All weak? Couldn't buy that.
Tried a few things, took a break and came back.
Started twisting the string to try and find a sweet spot. (quiet & smoother)
All went along with the weak spine idea until I hit right at 6" brace. Suddenly the 55 to 60# arrows started to straighten so I twisted a couple more.
Interestingly, the 55,60,65, &70# shafts went slightly stiff by just a little.
Not sure what you're shooting, But for me I think the huge amount of shoot around killed me. With the low brace the arrow was held tail right to the end of string travel, then the bow would whip the nock to the left getting around the handle and and stayed that way.
That' only an assumption. I was testing @ 10, 15, and 20 yds. all bare shafts.
Maybe my experience will give you an idea or 2?
Anyways, I'm considering a little heat bending to try and line up the string a bit. Just feeling shaky about messing with a (sorta) finished osage self bow. Having some limb twist on one end too, so I don't know if I really have anything to loose if all goes wrong.