Think I screwed up with arrow choice

[45-90scout]

Shooting a Nitrum 34 (not Turbo) set at 50 lbs, 29" draw length and arrows cut to 30". When I bought the bow it was recommended I use the Hexx 400 with 100gr field points - This according to the bow shop and Easton Chart. Shoots and groups beyond reproach @ 20 meters

This spring I talked to a few archers and made the comment, I'd like to go with a heavier point in the 125 -145 grain range with this arrow. These are screw in points. It was suggested I go with a stiffer spine, and so I did. Picked up a dozen Hexx 330's. and fletched them with FlexFletch 1.87 target vanes in a helic pattern.

Under the impression a stiffer spine results in less arrow flex = tighter groups. My groups opened up considerably.

Wondering now if maybe I need longer vanes to stabilize the heavier point?

Experience greatly appreciated.

[catnthehat]

Did you go up in your broadhead weight?
Everything has to balance basically a stiffer spine will need more weight tier ward to help it stabilize, which in turn will need more fletch behind it as well - in theory anyway!
Today with modern compounds arrows don't have to have as much archer's paradox to shoot straight because of the design of the rests and risers .
Cat

[jlgsgw]

Originally Posted by 45-90scout

Shooting a Nitrum 34 (not Turbo) set at 50 lbs, 29" draw length and arrows cut to 30". When I bought the bow it was recommended I use the Hexx 400 with 100gr field points - This according to the bow shop and Easton Chart. Shoots and groups beyond reproach @ 20 meters

This spring I talked to a few archers and made the comment, I'd like to go with a heavier point in the 125 -145 grain range with this arrow. These are screw in points. It was suggested I go with a stiffer spine, and so I did. Picked up a dozen Hexx 330's. and fletched them with FlexFletch 1.87 target vanes in a helic pattern.

Under the impression a stiffer spine results in less arrow flex = tighter groups. My groups opened up considerably.

Wondering now if maybe I need longer vanes to stabilize the heavier point?

Experience greatly appreciated.

Did you paper tune it after you changed arrow set up? If not I'd start there to get a good idea what issue you caused by switching up so you have an idea what you have to adjust to get things better. That said you may never get them to group as well as the arrows that were meant for that bow.

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[catnthehat]

Check out the tuning sticky at the top of the page!
Cat

[3blade]

Why? And why? And why????? Sorry

I don't think you understand the fundamentals of arrow performance. The goal is to have an arrow that flys straight. Adding weight to the tip to increase FOC is only necessary once you know that is your problem...most of the time the problem is a bow that isn't tuned right or an archer that isn't dialed in. You have to be very, very consistent to notice the difference a FOC change would cause.

Follow these steps:

Spec tune by trusted bow shop

Paper tune at bow shop, with a knowledgeable staff member watching your form

Shoot lots, if your groups are <4 inches out to 50 yards proceed to broadhead tune. If your groups are consistently the same size (for several sessions) but >4 inches at distance, go ahead and add a heavier field point. See if they tighten up. If they do, you re-paper tune, shoot lots, get sub 4in groups, then proceed to broadhead tune.

From experience, there is a very good chance a 330 is way over spined for a 50 lb bow regardless of cam design (you have to use adjusted draw weight, but I don't think it would get you over 55 adjusted so they will still be overspined) My guess is the guys you were talking to assumed you were shooting 60-70 lbs.

Your vanes are fine.

[45-90scout]

No I did not tune the bow after I switched arrows. How dumb............
Will do next weekend.

[jlgsgw]

Originally Posted by 45-90scout

No I did not tune the bow after I switched arrows. How dumb............
Will do next weekend.

It's not dumb, just learning as you go along as everyone has done or is doing, I can't say for sure you'll get that arrow set up perfect but without a doubt you'll get it good enough to harvest an animal at 40 yards and under, after that you really start to see a big difference when shooting a set up that's not ideal.

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[catnthehat]

Originally Posted by 45-90scout

No I did not tune the bow after I switched arrows. How dumb............
Will do next weekend.

It's a learning thing .
None of us came out of the womb knowing everything - except for maybe Rugatika!!
Cat

[L.O.S.T.Arrow]

Agree with the rest of the gang...Murphy's and Newton's law...For every action there is an equal and opposite re-action...meaning yes drastic changes like that will dictate some bow tuning...paper tune, walk back, etc are good places to start...

Neil