bareshaft tuning/wooden arrow spine

[gringol]

So I finally tried to bareshaft tune my bow today.  The results were a little troubling.  My bareshafts were hitting right so hard and so cock-eyed that I actually broke two.  I'm shooting a hill-style mild R/D longbow 70#@29"  (I'm drawing 27" so actual weight is around 65#).  I'm shooting ash spined to 70# with a 160 grain point.  Bareshaft tuning suggests that I'm way underspined, so the question is, how exactly are marked arrow spines determined?  My arrow setup seems pretty reasonable (the point isn't extremely heavy) and according to the marked arrow spine I figured I'd be a little closer to the correct spine than I appear to be.  Any thoughts?

[Prairie Drifter]

If your using 28" arrows,and using 160gr heads I would say you need 75-80# spine at least.

Wow...I think you will get a ton of info soon enough.  

The first thing I think of is if your arrows are actually spined 70# or within a range - 65-70   or 70-75.  

How close to center is your bow cut?  If your arrows are behaving too wimpy, take off the 160s and try a 125 and/or decrease the length of the arrow in increments(BOP) to further stiffen.

I like "Stu's Calculator" to give me a beginning point for proper arrow selection.  It takes into consideration many parameters such as spine, draw length, bow weight at draw, string type, point weight, etc.

Good luck and don't give up!

[Orion]

If you were shooting anything other than a hardwood, I'd say you were pretty close on spine.  However, hardwoods don't recover as fast as soft woods like cedar, spruce and Doug fir.  Thus, you do need a little more spine for them.  With a 160 grain head, i'd say about 75#-80#.  If you drop to 125 grain head, the 70# shafts might still work.

 BTW, I don't bare shaft wood shafts.  They just don't respond like carbons.  Slapping arrows into the target at an angle and breaking them is quite common with wood.  Build a few arrows with the spine you think you need and shoot them.  Keep doing that until you find a shaft that flies good for you.  Then remember its specs.  Good luck.

[gringol]

my arrows are spined in the 65-70# range.  I'be been shooting with 5" native cut feathers and never noticed a problem until I switched to 4" shields.  I off hog hunting in two weeks, so its back to the natives and I'll tackle this later.  S Thanks for the info, guys.