switch from 125 to 100 grain
 

I want to switch from a 125 tip to a 100 tip. I shoot easton axis st arrows 340. I shoot an allegiance bow at 70 pounds and 28 1/2 inch draw. I was told that if i changed my arrows would not be spined correctly. is that true? If i changed without changing my arrows, what would that cause, other than my sites being a little high. Any help would be appreciated.

Thanks

Only way to really tell is to BH tune the bow.

Computer programs and graphs can only get you so far. 125gr will weaken the spine a tad. Not that much however. If your spine of your arrows are in the middle now, it will push it to the weak side which can be recovered by cutting an inch off the arrows or moving the rest slightly.

You're going to a lighter tip, which will gain spine (true, only a little). Reducing the overall weight of your arrow will gain you a little speed too. Whenever you change some characterisitic of the arrow you can expect them to impact a few inches left or right (or high or low) of where they did before. Assuming your arrow spine is good for your draw weight, if they fly well, and BHs and FPs fly comparably, adjust sights. If not tune the bow. You won't get an underspined arrow to fly well with BHs (except some mechanicals). You can get an overspined arrow to fly acceptably with BHs.