Right arrow spline.

[87TT]

Have shot it like this since last year and it seemed to work OK but as I get more experienced, I wonder if it could be better. I have some 100 gr heads I may try or possibly leave out the 50 gr insert. Trying to figure out the calculator just hurt my head. In the process right now of tuning a new bow. Trying to do it all myself. On the upside, the bow press I built is working awesome. So much to learn.





Sorry for the hijack

 

[nphunter]

Have shot it like this since last year and it seemed to work OK but as I get more experienced, I wonder if it could be better. I have some 100 gr heads I may try or possibly leave out the 50 gr insert. Trying to figure out the calculator just hurt my head. In the process right now of tuning a new bow. Trying to do it all myself. On the upside, the bow press I built is working awesome. So much to learn.

Sorry for the hijack

Weak spine can shoot great, stiff spine can shoot great. I base my equipment off of experience and how they shoot. I was shooting a A/C injexion a few years ago, I should have been shooting a 350 spine. Calculator showed .355 to be ideal. The 390 Injexions shot awesome out to 70 yards with fixed heads. No idea why but since they shot so well I kept shooting them, killed several animals with them.

Everything in archery is estimations due to multiple variables with equipment and shooters. Real life testing always trumps an online calculator or someone else’s opinion or experience. If your bow shoots great then leave it, if it doesn’t shoot as well as you feel you can shoot then make some adjustments.

John Dudley has some good info on determining spine, look up the HIL Method. You can test spine easily by just adjusting draw weight. If you back your limb bolts out a turn and your groups shrink then your under spined. This only works when all other variables are the same and should be looked at on the average of several sets of groups. You can do the same thing by having multiple head weights and shooting them and checking grouping.

Broadheads are a different animal, little things like squaring, speed or any other inconsistency’s can make a big difference with Broadheads. Typically inconsistency’s with groups are either related to form or arrows, even poorly tuned bows shoot consistently unless there are contact issues.

 

[nphunter]

Sorry for the hijack

Not really Hijacking I think it’s relevant to the OP’s questions and can help him with his questions as well.