Arrow spine on a cut to center shelf RD LB

[Huntschool]

OK....  So, the question is ..  On a cut to center modern RD LB, shooting off the shelf with about a .124 strike plate thickness can a higher/lower then normal spine shaft be used.  I would like to shoot 100 gr. points or close to that number. I know there are determining factors such as release (mine is really good with between 1 and 2 fps difference between releases checked on a chrono).

I am trying to get the fastest speed I can get with a 29" draw  with a 29.5"  arrow out of a 38# +/- bow. This is for 3D with field points only.

Thanks in advance.  If this post is in the wrong place feel free to move it.

[Orion]

Can use a higher spined shaft than a bow not cut to center, i.e., proud of center.  If you're asking what spine to try, I'd suggest .600s, given that you're going to put a fairly light point on them. When you say modern r/d longbow, I'm assuming it's a strong r/d hybrid with a low stretch string. 

[Huntschool]

Can use a higher spined shaft than a bow not cut to center, i.e., proud of center.  If you're asking what spine to try, I'd suggest .600s, given that you're going to put a fairly light point on them. When you say modern r/d longbow, I'm assuming it's a strong r/d hybrid with a low stretch string.

Orion:

Correct.  This will be a hot rod LB for 3D competition.  But will be shot with carbon arrows...  Yea, I know about the rules... LOL

[McDave]

I shoot pretty close to that.  Since you stated your bow is cut to center, but not past center, and you will be moving the arrow away from center by .124, it would seem that a slightly weak shaft would be called for.  At your 29” draw, you will be drawing about 40# on your 38# bow. I would recommend a .600 spine Gold Tip Ultralight or similar shaft that weighs about 5.9 grains per inch.  You might want to start at 30” rather than 29.5”, and try a 75 grain tip.  This should give you an arrow weight of about 300 grains, or 7.5 gpp, which is about as low as I want to push it on a modern bow, and an FOC in excess of 10%.  From there, you can experiment with cutting the shaft back to 29.5” and/or upping the point weight to 100 grains to see what gives you the best arrow flight.  You could also experiment with a 50 or 65 grain point, which should still give you an FOC in excess of 10%, but will drop your grains per pound below 7.5, which may or may not be acceptable to you.

[Huntschool]

McDave & Orion: 

Thanks guys.  I have some shafts inbound that match your thoughts.