?Spine diff between .400/.500 deflection?

[Bowmania]

Hypothetical question?  I have a 30 inch .500 deflection arrow with 200 grains up front.  It flys perfectly from my bow.  I want a heavier arrow.  With all the options we have today, I should be able to add 400, 500, 700, grains to the front of a .400 arrow and make it fly as perfectly as a .500.  Anybody know how much that would be???

And if that was a 28 inch arrow would the amount be the same?  Actually I'm sure it would not or it would be in Stu's Calculator.  LOL!!!  I would guess that since the shorter arrow is stiffer it would need more weight.

Bowmania

[JimB]

Roughly 100 grs of point weight going from .500 to .400.There is app 20 lbs of spine difference.To change dynamic spine 5#,bows I own go from 15-25 grs.It would depend on the bow but I would experiment with adding 100 grs first,with .400 deflection.

[mark land]

With my Beman MFX arrows I can bare shaft them to tune the same with a 500 at 28in and 225grs of tip weight and the 400 at 30in with the same tip weight off my 54 and 56# BW bows.  My 500 wieghs 520grs and the 400 weighs 560grs.

[Old York]

I think some careful data entries into Stu's DSC would get you into the ballpark, just choose "OTHER", run the deflections through his ASTM to old AMO converter, etc.