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In need of advice

Overspined, I’d say start with full length 500 spine shafts and slowly cut away 1/4” at a time until they fly well but don’t cut to short. the cut of your riser will also play into this but I’d add a few 100 grains or up in spine.
for example, I’m shooting 29.5”400 spine with 350grains upfront from 45# at 28”.
 
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To go along with the above, I’m shooting 31” 400 with 320 grains up front from a 42#@28” longbow.

The center cut of the riser is the most overlooked aspect of bow tuning in my opinion. That Prairie Predator is cut somewhere between 1/8-1/4” before center. That’s anywhere from one to two spine groups of a difference from center cut.

Still curious what your current arrow length on the 400 is?
 
Another way to look at it would be, do you have a specific broadhead or tip weight you want to hunt with? If you say you want to use a 200 grain broadhead with a 100 grain insert you can leave that constant and you can play with the arrow length to get to the spine you right. Since you have a fairly short draw you could really play with the arrow length. Starting with 30” arrow and the known tip weight you want, shoot the arrow and see how it kicks. Then take off a 1/8” or a 1/4” at a time and shoot the arrow and monitor your kick. In this scenario you would be starting with an underspined arrow and working your way up to the correct spine. If you take a pic after each length cut you should see the arrow starting to stand up to center.

If you are not willing to shoot a longer arrow, then you will have no choice but to add weight to a heavy spined arrow or take off weight from a underspined arrow to get it to fly true.

I have some both methods and both work. You do need to listen to the way your arrow is kicking and go from there. If buying new arrows to work with and cut is not in the cards you might need to get heavy like everyone is saying but at that point you’ll be buying new inserts and new broad heads likely.
 
Anobody said:
28 ish
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If you have any 32” full length 400 arrows you should give those a shot. Like I said, I’m at 31” and I know my bow is cut close to center than yours. That allows me to shoot a stiffer spine arrow.
28”/.400 deflection = 70# spine. That’s using the ASTM formula to determine bow weight spine.
 
Anobody said:
28 ish
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I'm shooting essentially the same setup, but with a different bow. 400 spine but with 150 grain insert and a 150 grain broadhead. 50# at 28", Lefty. Mine was acting over spined with anything less than 300 total grains up front with a full length shaft. But full length with 300 grains up front wound up being perfect.

And these are the arrows I traded from you last year!
 
Your bare shaft is extremely stiff. The arrow is not bending around the shelf. If it was pointing to the other side it would be noodling around the shelf facing back toward the right. I shoot a 50lb at 26 bow and draw 26. So we are within 2 lbs of each other. I also shoot a 400 spine arrow but I have 200 up front and a 30.5 inch arrow I believe. Throw your setup in a spine calculator and I believe you’ll be way off to the stiff. If you want to keep the 125 heads you’ll need a 500 spine and a long arrow.
 
Easy….way too stiff. 28-29” 500 or Gold Tip 35/55 with 175-200 up front. Same arrow I shoot from my 50# recurve.
 
Petrichor said:
Your bare shaft is extremely stiff. The arrow is not bending around the shelf. If it was pointing to the other side it would be noodling around the shelf facing back toward the right. I shoot a 50lb at 26 bow and draw 26. So we are within 2 lbs of each other. I also shoot a 400 spine arrow but I have 200 up front and a 30.5 inch arrow I believe. Throw your setup in a spine calculator and I believe you’ll be way off to the stiff. If you want to keep the 125 heads you’ll need a 500 spine and a long arrow.
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I put his info in the spine calculator and dynamic arrow spine was 90#! Even with a long 500 using 125 was too stiff.

If you want to go shorter arrow and 125 heads, it will require a 600 or 700 spine arrows.
 
JSEXTON23 said:
I put his info in the spine calculator and dynamic arrow spine was 90#! Even with a long 500 using 125 was too stiff.

If you want to go shorter arrow and 125 heads, it will require a 600 or 700 spine arrows.
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Wow. Thanks for putting it in. I was gonna do that but got put on a project at work. I play with a spine calculator all the time. Great tool and I think my setup ended up being just 1/4” off of where the calculator told me I’d be once I was tuned.
 
Anobody said:
Alright guys going black Eagle 600 spine with 8gpi tube and 125 head. Wish me luck
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God speed brother! Pm me if you want to try some heavier point weights too, I got the ranch fairy set thats 200-300gr test points if needed.
 
SnakeEater said:
God speed brother! Pm me if you want to try some heavier point weights too, I got the ranch fairy why is 200-300gr test points if needed.
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Will do I have heads up to 200 but really don’t want to buy more broadheads
 
No sticking to same length. Lightest shaft black eagle makes tubes will help with mass I’m not as worried about FOC
 
Man, I want to be wrong, but a 600, with a normal 10-12 grain insert, cut to 28” long from nock throat to insert is going to spine around 60#. That bow at your draw length spines around 40#. Those arrows might be too stiff with 125. And by might be, I’d be willing to wager dollar bills.

I hope I’m wrong.
 
JSEXTON23 said:
Man, I want to be wrong, but a 600, with a normal 10-12 grain insert, cut to 28” long from nock throat to insert is going to spine around 60#. That bow at your draw length spines around 40#. Those arrows might be too stiff with 125. And by might be, I’d be willing to wager dollar bills.

I hope I’m wrong.
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If I go 150-175 gead?
least I’ll be closer not as grossly over . If I have to buy insert weights or a bigger head I can use the 125s on the boys Xbow
 
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