Heavier # limbs require WEAKER spine???

[GMMAT]

OK....so I've been shooting 3D with my 50# set of limbs (60" bow). I'm shooting a CX Heritaage 250 @ 30" w/ a 175gr. FP.

I switched over to the 56# limbs, today, to bare shaft tune (62" bow). I wanted to find out what I needed to build my hunting arrow. My findings were interesting.

My hunting arrow will be nearly identical to my 3D arrow....but 1" longer. Hows that possible? I do have a quiver mounted at my limb bolts, but that's the only difference. Same riser.

I chrono'd the 50# limbs @ 171fps. I chrono'd the 56# limbs @ 181fps, today.

What could make the heavier limbs need a weaker spined arrow? Overall bow length? Quiver (loaded with 3 arrows)?

[Orion]

You probably just have more spine than you need with the lighter set of limbs.  Most bows will shoot overspined arrows quite well.  Your heavier bow will no doubt shoot even heavier spines well also.

[GMMAT]

Orion....I don't doubt you, but I've bare-shafted extensively with the 50# limbs.  I can't shoot 150's.....and I can't shoot 250's (same length) with lighter FP's (stiffer spine).  It shoots what it likes....and I don't try to influence it too much.

I can't shoot even the SAME arrow out of the 56# limbs that I shoot out of the 50#'ers.  I can't explain it.  It's either a freak of nature; the overall bow length or the quiver loaded w/arrows.

[Steve O]

Take the quiver off and see what happens.  I doubt that is it though.  

I just did the exact same thing recently except for the changing of bow length and found the same thing.  I chalked it up to once you get the carbons tuned in, they are pretty forgiving and I was on the stiff side of tuned with weak limbs and the weak side of tuned with the heavy limbs...

[vermonster13]

Have you scaled the 56# limbs? Are they made of the same materials? Other variables come into play.

[GMMAT]

They're not the same veneers.....but it's a 3 yr old Shafer Silvertip.  I haven't put the limbs on a draw weight scale and likely won't (what's the point?).  The gentleman I bought the bow from said the bow had never been strung with the 56# limbs.  It had 2 new strings for that set of limbs....and I got the 1st one out of the package.

This bow's a LOT more finnicky than the RER was.  Ive gone on both sides of where I am, now, with both sets of limbs.  It likes what it likes.  I can't explain it, though.

[James Wrenn]

The quiver effects things.That is why you tune with a quiver and arrows on the bow if you are going to use it that way.The different balence makes the bow move different on release.Most times you use a bow quiver you will need a weaker spine than if not useing one on the same bow. jmo

[GMMAT]

James....

I was at Page's house tuning the bow I'll be hunting with, this morning.  It was perplexing to both of us.  I've had Page present each time I've tuned arrows, so far.  If there's someone more in the know, I don't know him.

I just thought I'd see if anyone else had experienced this.

[Bjorn]

GMMAT you got a 10 FPS gain, which is about right for 6#, and contradicts any ideas of shorter draw and other inefficiencies, which could otherwise be associatred with the new spine issue. It is likely as you say.......it wants what it wants. Fortunately there is more art than science to this obsession!
Maybe check the string alignment with each set of limbs-is it possible that the string lays 'right'  with the heavier limbs?

[GMMAT]

Bjorn:

I'm not sure what you mean by string alignment.  Sorry.  My friend was watching my draw to make sure I wasn't short-drawing the heavier limbs.  That wasn't an issue.

If you'd explain string alignment, I'd appreciate it.  Short but sweet is fine!

[A.S.]

Are the strings the same (# or strands etc)?

Could you possibly have more string sliencer on the string for the heavier limbs?

Just a couple more things to look at.

[HATCHCHASER]

You may be getting a cleaner release with the longer bow.  I also agree with A.S.

[Bjorn]

GMMAT, it is what it is and go with it. You got the speed increase from the heavier limbs; and you bare shafted with the proper result-spine is just a number anyway.
Good luck hunting and don't forget the pics!  

[GMMAT]

Same string.  Both are the ones that came with the bow (both were new in the last few weeks....as I put the new strings on when I got it).

I put yarn on the heavier limbs.....and the lighter limbs have beaver balls.  If anything, I'd say they're similar.

I appreciate it!  Really.  We went through these things while tuning.....so we're thinking alike.  

It's just interesting, to me.  I'm still new to this aspect of trad. archery (new to all of it, actually).  I can't figure (in my head) if the added length would affect this.  I can (in my head) understand a heavier (mass weight) bow not clearing (I hope that makes sense) as fast as a lighter bow (on the shot).  I can imagine a more stable bow (not moving on the release) requiring a weaker spine.

[GMMAT]

Thaks all....and Bjorn....I have my eye on two deer.  If I'm successful, you won't have to worry about a photo!....lol

Thanks again, guys!

[Kris]

Orion is right.  There is nothing at all surprising about this.  I shoot Heritage CX 250 Classics through my 57# Silvertip and I could take these same arrows and shoot them through any lighter bow.  Arrows and their specific spines have a fair range of bow weights for which they will work through, and isn't that nice.

[Kris]

http://www.carbonexpressarrows.com/images/2009_Arrow_Guide.pdf

Carbon Express arrow chart says HE 250's will work through a 50# or 56# bow at your draw length.

[Big Ed]

Different tiller, core materials, Maybe even a cleaner release with the heavier weight

[GMMAT]

The bow was ordered with both sets of limbs (both tillered by Dave...but I guess it could be different....at some minute level).  

THE ARROWS that fly correctly from the 50# limbs......are TOO STIFF for the 56# limbs.  Sure the 250's will work for both.....at some length and with some amount of tip weight.  But not the same arrow (I would be VERY surprised).

I'm MORE surprised it wants a weaker arrow, though.

[Kris]

Have you tried the exact same arrow (you said you would be surprised) through both limbs?.  What indicators are telling you those arrows are too stiff for your 56# limbs, are you sure you don't mean they're too weak?  I do a lot of bare shafting testing with my Silvertip, using these arrows, amongst many others, so I sincerely mean to offer some help, if I can.  I have found that the CX Heritage shafts tend to be weak, per they're claims.  I sent HE 150's back to 3 River's for this very reason.