Half-out effect on stiffness

[jkl_2022]

I am building some 300 spine RIP TKO's using SFAX.

My question is how will the 75 gr Shok insert affect stiffness other than the weight? I am accounting for the added 75 gr weight in SFAX but not the change in arrow length or stiffness as a result of the Shok insert. The Shok should add about an inch of length.

 

[Bump79]

You won't notice much of an increase in stiffness

 

[Billy Goat]

I can find a difference with inserts/points that are longer. I was playing with some 3d arrows this week that had long glue in points. I removed 20 gr from the point, which took almost 3/8" off of it. Should have made the arrow react stiffer with less weight on the front, but seemed to act weaker. Not the first time I have seen it. I put long SS inserts in some .246 shafts before and noticed it then too.

Didn't think either would be enough to notice. Just playing with the arrows I previously was using, at distance the new arrows initially hit left, after removing the back of the point (3/8" and 20 gr) they started to impact to the right of the old arrows.


I generally don't get too wrapped up in left/right impacts in regard to spine on a centershot compound, but I couldn't ignore it either.

The old arrows I had were on the stiff side already. Groups tightened up a bit with the reduced point weight and longer "free shaft" on the new arrows.


For the most part I think it can be ignored, but if you are on the weaker side of the spine you can count on it being a little stiffer than what a program will tell you.