Spine tolerant

[bartcanoe]

I posted earlier about wanting to shoot wood arrows our of my new-to-me 70" Two Tracks Echo 64@28 (drawn to 29.5)

To that end, I ordered a 3Rivers Hunter Arrow Test Kit cut BOP 31", fletched and with 190gn point up front.

The kit had 8 arrows.  

2 - 65-70 spine, weight 570gn and 624gn
2 - 70-75 spine, weight 632gn and 604gn
2 - 75-80 spine, weight 672gn and 618gn
2 - 80-85 spine, weight 620gn and 636gn

With these arrows (minus the 570 gn, 65-70), I headed to the range.  To my surprise, with the exception of a few flyers the arrows consistently grouped together (within my poor shooting abilities).

This makes me think that I could add some more weight out front on the 80-85 spine, and be set with the right spine and the weight of arrow I'm looking for.

[Orion]

Yep.  Most bows are quite spine tolerant.  They'll shoot a range of spines to the bull, and look good doing it, if we do our part.

[gringol]

Try the test again with broadheads.  Any spine problems will jump out.  Fletched arrows with field points are very for giving; bhs not so much.

[Stumpkiller]

With a centershot recurve you can get away with a wide spine range - especially overspined.

[bartcanoe]

Originally posted by Stumpkiller:
With a centershot recurve you can get away with a wide spine range - especially overspined.

That's what surprised me, the Echo is a straight limbed, not centershot longbow.

I'll have to try broadheads like gringol suggested.

[bigbadjon]

Your bow will only have one dynamic spine that flies well no matter how much centershot a bow has. Fletched arrows won't mask a poor match as you get better.

[Orion]

True, there is only one theoretically optimal spine for a given bow/arrow combination, but few of us have form good enough to find it.  

Luckily, most bows will shoot a range of spines WELL, particularly overspined arrows, as Stumpkiller notes.  For example, I can vary the spine of my arrows by 15# on my ACS bows, and get arrow flight that's perfect to the naked eye and hit what I'm shooting at.  That's good enough for me.

Take a look at the "Old School" tuning thread for lots more examples.  I've been shooting sticks for more than 50 years and have seldom had a problem getting extremely good arrow flight, and I'm sure some my arrows weren't perfectly matched to the bow. I'm not nocking the latest spine calculator/formula. I think it's an excellent tool, but we managed to get good arrow flight long before that tool was developed.