Arrow spine or 3 under

[thump]

My Fox recurves are all tillered for split finger.My arrows are cedar 540grn and 55/60 spine cut to 28" with 125grn pt.My Fox Royal crown was bought from the classifieds and is 48#@28".When I shoot the longbow with these arrows I get a little bit of porpoising.When I shoot with three fingers under the arrows fly fine,then I switched to one of my sons arrows also cedar 470grn 28" 45/50 spine the fly like darts using my normal split finger release.Any thoughts?  Thank Luke    

[xtrema312]

I have some variation between spine need shooting split and three under.  I am not sure why, but I assume it is how clean my release is between the two styles.  Try adjusting your nock for the porpoising.  A LB of the same weight as a curve will probably need a little weaker shaft plus they may not be cut to the same degree of center cut or have different side plate thickness.

[thump]

Thanks Xtrema its probably my release and arrow spine. I was thinking the bow was tillered for three fingers under.

[xtrema312]

Make sure to play with the nock height.

[Jimbow39]

Check the centershot amount of your bow. If it is out from center rather than past center, it will require a lighter spined arrow.