Tuning from 125 grain to 150 grain heads

[stick_string]

Shooting 56# and 29inch arrow at 28inch draw from Black Widow PSA.  When making the switch to 150 grain head I get nock high and right on a bare shaft how do I get it straight?      :confused:    

[AnointedArcher]

Well hitting right usally is a sign of and under spined arrow?  The extra 25 grains on your tips might of been enough weight to take spine strength from you arrow.  If your arrow wieght is spined right at the border line adding weight to your arrows would cause you to loose some spine.

[stick_string]

So do I lengthen the arrow or shorten the arrow?

[Jeremy]

Are you talking about nock position or where the arrow impacts compared to fletched arrows?  

What AA is talking about is the bareshaft planing method of tuning where you DON'T look at nock position, but rather where the arrow impacts compared to fletched shafts.  (He's spot on BTW with the weak spine if you're a righty).

If you're looking only at nock position, well, that can be extremely misleading as the target material has a big impact on how the arrow leans.  "Nock right" normally leads to the impact to the left, which indicates an overspined arrow.

[swampbuck]

adding weight up front weakens the spine,cutting them shorter will stiffen it up.You can also pad the side a little if you don't wish to cut some off your arrows.You may wish to go back to 125 some day for what ever reason and it'd be easier to remove the side padding than add 1/2" back on to your arrows.

What the other guys are saying is correct.I'd also make sure your not nock isn't low to the point that the arrow is bouncing up off the self.....I'd cut only after other options are checked out.It's not easy to put it back on all though with wood I've seen it done.Good luck

[Kingstaken]

Nock right for a righty is stiff, for a lefty is weak.. Into the riser is stiff.
Are you getting arrow right or nock right?
Arrow right makes sense cause by adding weight to weaken the spine.
Don't confuse nock high or low if you cant the bow.
Shoot with bow straight up for tear.

[stick_string]

I am getting nock right.  So I guess I am under spined but the arrows are cut to 29inches and my draw is 28inches.  With that said I am guessing that I will have to go another route with my arrows or stay with 125 grain heads.  Does that sound right?  :confused:    

[Jeremy]

Are you right handed or a lefty?  If a lefty then yup, you may be underspined.  Verify that before doing anything else by building out your sideplate slightly.

What arrows are you shooting?  A lot of times if you're way overspined you end up getting an "underspined" indicator... just another thing to complicate matters.

[stick_string]

I am right handed and shoot Easton aluminum xx75 2216 arrows at 28inches. I want to shoot heavy arrow so that I have the best chance at a pass through.  I do not remember the exact number but the arrow is around 550 - 580 grains in weight.

[Jeremy]

OK, now we're getting somewhere!     The 2216's spine out at 84# at are WAY overspined for your set up.  2018's would be a better choice with those heads, or maybe 2020's.  Or you could add a cubic-$h**-ton of point weight to soften them up some.   BTW, that's a precise, industry wide accepted unit of measurement!  

[BLACK WOLF]

Black Widows tend to require arrows of stiffer spine. My 69lbs. Black Widow needed 2419s, which spine around 100+ lbs., cut at 30.5" with 160g. points.

I also have seen arrows so stiff that they actually will indicate a false reading of being to weak.

Do as what the others here have suggested. As you get more feedback from experimenting it should lead you to the answer you're looking for.

Ray  

[stick_string]

Yep, I asked the folks at Black Widow what the best arrow would be to shoot and they recommended the 2216 due to weight.  With the 125 grain heads the arrows come out to about 550+ grains in weight.  

Is there a good method to calculate spine according to poundage of bow?

[Jeremy]

There's a good spine chart here:   Foxfire  

It's a nice place to start