Crazy Spine Tuning Variables???

[BAbassangler]

So I'm playing with a 40# 64" ILF longbow, and got good bareshafts with 500's and HFOC.  I want to make use of some 600's I have so figured I'd be OK with back to 1980's FOC and 125 grain points, not so much!

The 600's also wanted HFOC and I ended up with 320gr total up front; but with nock high...until I moved my string silencers closer to the tips, (from 13" to 9 3/4").  Now all of a sudden I'm capable of tuning a nock low condition, (accompanied with tail left/weak).

Is this crazy or what?!?  Does anyone know what's going on, I just like to make sense of things and learn as much as I can.

Samick Discovery 17" with XL DAS bamboo/glass
Elevated rest to center or just out from 1/16"
28.5" DL
29" Axis 600 with stock HIT + 310
Brace 8 1/16 - 8 1/4 seems to be practical sweet spot

[Orion]

With a bow cut past center on which you can control the amount of center shot, it's possible to tune for an arrow that would be overspined on less center shot bows.  Thus, the heavy foc on the 500s, which at about 63# would normally be considered heavy for a 40# bow.

Even the 600s (52# spine according to Easton charts) can be front loaded a lot. 320 up front is probably the max.  My guess is the arrow would shoot fine with less up front as well.

Though there likely is one optimal bow, arrow spine, shooter combination, most bows will shoot a range of spines well, and bows with adjustable arrow rests/side plates will shoot the widest range of spines well.  Long story short, I don't see anything unusual in your results.       

I doubt string silencer position has anything to do with your results unless they are extremely large and/or heavy. 

[BAbassangler]

Thanks, TG
This helps. I don't have much experience with the lighter spines; and good to hear that 600's can take that much weight.  It was just odd that I could not get anything to shoot weak or nock low, until I mover the string silencers...don't get it but moving forward with this one.  Waiting on wraps and need to fletch a test arrow before I spin myself into a bareshaft stupor,