one inch arrow length=how many grains?

[brackshooter]

Say you took two identical arrows, lets say full length beman ics 340s.  They bare shaft perfect out of your bow.  Now lets say I cut one inch off of one of them.  This obviously would stiffen the spine.  How many grains of weight up front would be needed to cause them to fly the same again?  Is there a hard and fast rule, or is it variable based on bow, shooter, and arrow?
Hope this makes sense.

[WidowEater]

definitely variable on bow weight for the same size arow, that is all i know though, trial and erroro is the best medicine

[Shawn Leonard]

No hard and fast rule, if ya take a whole inch I think you need at least 75 grains to soften them back up again if not more but on a weaker spine to begin with  like a .500 I would say ya may only need a bit more than 50 grains or so, it has too many factors to say for sure. Like the bow, how center cut and so on. Shawn

[Blackhawk]

My guess is there is no hard and fast rule, and is based on the variables you mentioned.  

Cutting an inch from a 31" arrow for someone with a 27" draw would probably require less weight up front (if any).  

However, cutting an inch from a 28" arrow with the same 27" draw may require 100 grains or more to attain perfect flight.

As a final note, I have found cutting 1/4" off the arrow would require the adding of about 20-25 gr. more weight.  (notice I used the word "about").

[agd68]

I asked a similar question with regards to broadhead wieght affecting spine.Fellow member Hamish said he had researched the topic and found that +/- 25 grains head wieght had similar affect as +/- 1" of shaft lenght on spine: so 1"=approx 5lbs,25grains = approx 5lbs

[brackshooter]

Interesting stuff guys.  I have a HH that shoots full length 340s great with 300 grains up front.  Would really like to use 350 up front for convienience.  How much would I have to take off to make the 350 work?  I would like to take off an inch, but Im not sure if it would be too much or not.  May just have to experiment.  BTW, I have a 30.5" draw and am shooting a 60@28 howard hill, about 68# at my draw.

[WESTBROOK]

I also think a given amount of weight has a bigger effect on a 31" arrow than say a 28". Sort of a leverage thing.

Eric

[BOWBENDERPA]

I only shoot aluminum but read somewhere years ago that an every extra inch of arrow length needs 5 more # of spine and also that 25 extra grains of point weight requires an additional 5# of spine.  If the same holds true for carbon arrows - cut one inch, add 25 grains of point weight.

[wtpops]

through my bow its 25 grains