Thanks McDave!

[the rifleman]

I just got a new bow---a 56" Toelke PIKA.  It is 40@29".  I draw about 26.5" so around 34/35# at my draw.  I immediately found my Heritage 75s (.670 spine) way too stiff even with 200 up front and full length.  I had a 1716 (.880 spine) and found it bareshafted decently.  I fletched it and then found that no matter how much weight I added to the front it hit 3-4" to the right---I shoot left handed so thought that it was too stiff.  I read one of McDave's posts from April of this year and he explained that sometimes we get an opposite reaction with fletched arrows.  I dropped point weight from 125 to 100 and like he said my arrow moved to the left as if it was weaker.  I very much appreciate the wealth of information that I have gotten on this site---I'd sure be stumbling around in the dark without it.
I ordered some .800 spine predators and hope that they will tune for me.  Thanks again McDave!

[McDave]

You said you shoot lefthanded and your arrow was impacting to the right.  The general wisdom would be that this indicates too weak (for a LH shooter), rather than too stiff.  So you decreased the point weight (stiffening the arrow), and it moved your POI to the left, as one would expect.  I don’t think this is an example of the reverse effect that I wrote about, but it is does show that we have to keep an open mind when we are tuning with fletched shafts.  From what you have stated, I believe your .800 spine predators should work out well for you.  good luck!

[the rifleman]

Wouldnt a right impact indicate a spine too stiff for a lefthander?  Point impacting to the right of target and nock left position is what im getting bareshaft.

[McDave]

On second thought, you are correct. I must have been confusing my lefties and my righties. So my theory actually did work!  Yay!

[the rifleman]

Im looking forward to tuning the 800s.  I hope they are weak enough as the 1716 is .880 spine-- if not I'll be looking at 900s.  When i could get the chronograph to work it looked like speed was only a few fps less than my 42@28 w same arrows i shoot in that bow, so im surprised it is wanting such a weak arrow.  I did shoot shorter arrow w lighter tip to rule out a false stiff.

[McDave]

I will be interested to know how the .800’s turn out.

[the rifleman]

The 800s tuned good w 125 point and 38gr outsert.  Arrows full length.  I put a clicker on this bow yesterday-- first time ive used one.  Wow did it tell me about my form.  All of a sudden the 800s tuned perfect w 100 gr points and my heritage 75 that just barely tuned w 200 points now tune with 125.  Im always learning.  I believe the clicker is going to be a great aid in consistent expansion.