Weird spine reactions

[rendalen]

Hello
I have just changed from a fast flight string to a dacron string on my Bear take down due to noise. Put a dacron string on and it is dead silent. Brace is 7.8 and i have a verry thin sideplate. When i started shooting i had some weird spine reactions. When i shot fast flight i needed a 2016 cut to 28,5 on my 42# limbs and 2018 cut at 28,5 on my 47# pound limbs. When i changed to dacron 14 strand string on both set of limbs i had to go down to 1916. When i started testing i cut my first arrow to 29, that was flying dead straight. But i want it to be a little weak so when i put my feathers on it stiffens the spine a little. So i cut one to 29,5 still dead straight. Left the last full lenght 30 inches, i draw 28. And that one gave me one inch weak at 20 yards barshaft on both set of limbs. How is this possible ?
I should to be able to shoot that shaft out of my 47# bow. And i have never had better arrow flight. What is going on ?

Øyvind

[moebow]

Oyvind,

If I understand what you are asking correctly;  it is how you can shoot the same shaft (1916) with both sets of limbs.  I think you have found the best spine for your two setups and when you do that, there is a weight "range"  where the spine works.

I can understand the 2016s working well with the fast flight string but I also think that 2018s are too stiff (again with the fast flight).

In my experience, 1916s are the "go to" shaft for the 40 to 50 pound bow weight range with Dacron strings.  I generally can shoot a given shaft out of multiple bows and bow weights.  A far larger range than many would have you believe.  

The real bottom line is IF the shaft is working for you and your set up(s), don't get too worried if the results are different from "common opinion."

Arne

[Orion]

Agreed.  Most bows will shoot a range of spines well.  We worry too much about tuning to the last twist of the string. I mostly shoot woods and arrows spined from 50# to 70# shoot well out of my 47@28 and 52@28 limbs on my Bear takedowns with D-97 strings.

[DawgDoc]

Agree ++ with the above. There often seems to be a spine range that works sometimes. Also agree with Arne about trusting your testing on your set-up. A bow shoots what it wants to in regards to spine. Sometimes the results do not follow popular opinion regarding spine and sometimes results are confusing. Your bow likes what it likes. If it makes you feel better I'm shooting a Bear T/D with 57 lb limbs at my 29.5" draw, and I'm shooting a 500 spine 30" arrow with 275 gr. point weight and its dead straight on bare shafting. That should be way underspined but thats what works on this bow.
Jay

[rendalen]

I have always been told that a underspinned arrow wil not shoot straight. Now i know different.
If the nock point is set at right height it seems to shoot almost anything.

Øyvind

Back in the day, if a 2016 was stiff and a 1916 was dead on, one could go to an 1818 if you wanted slightly less or a 1918 if you wanted something slightly stiff. I like those two shaft sizes for my lighter bows. I have had more issues 1916s and 2016s when going from field points to broadheads than with the 1918s when I had my Bear takedowns. Everyone is different, but a Bear takedown can shoot a wide variety of spines at your draw length. That's a really good thing, that can make us longbow shooters jealous.

[rendalen]

I had a typo in my first post. It should be full lenght 31 inches instead of 30.

Øyvind