I'm making a switch on my longbow from carbons to the Easton XX75 Legacy because I can get a bunch of em for less than retail, which is nice. I'm shooting em out of my 55 lb Abbott Longbow which is about 57 lbs at my DL. If my bow tuned with a .500 spine carbon will it tune the same with a .500 spine aluminum? I guess I'm asking if aluminum shoots differently than carbon at the same spine and point weight.

That seems weak for you set up. Im shooting 400s with 160gr tips out of a 53lb bow.

And those are full length arrows

my experience has been that easton carbons and aluminums same spine will tune almost equally well with same weight up front but have to leave carbons a little longer than same spined aluminum with same point.2117's and 400's are what arrows I'm referring to. Same spine between these are pretty consistant!!!But they are the same spine carbon usually or so it seems to me have a broader spine range than aluminum.

No the carbons are 29" overall, my carbons are .400 spine, I was using .500 merely as an example to ask my main question to help me decide whether or not to go with the same spine.

I am shooting 175 grain points on my .400 carbons, if I wanted to move up to a 200+ gr point would a .400 spined aluminum still be okay?

I find you can't really compare carbons and aluminum.If you are shooting 57# at your draw I would pick a 2018(.464 spine)or 2020(.426 spine) with a heavier point.A 2018 with a 175 gr. point will put you around 580 gr. range depending on the length.The 2020 will put you over 600 grs. with a 175 gr. point.

Good question...

Wouldn't diameter of the shaft also affect spine requirements between the two as well?  

If the carbon is 9/32nds and the XX75 is 21/64ths, wouldn't it be similar to building out the side plate and the aluminum shaft should require less spine as arrow diameter increases to shoot the same?

with my setup 55 @ 28,29" draw sliight rd longbow cut to center, an SBD skinny string, 2117 with 175 up front bareshafted and flew great, easton st epic 400 with 175 up front flew and bareshafted good,aluminum was 30" arrows, carbon 31", tried 2018's too weak for me, 2018's and surewoods fly better on my other bow just a little lighter #'s.SHoot what works for you woodies are my choice not always the bows, when I have dough will get some for this set up but will keep like it is for backup.Basic starting points the charts, the rest is up to you to decide Good luck!!!!

I think ill start by testing out some 2117's with my 175, 200, and 250 grain field points. I'll get back to yall after some testing.

So after some shooting of the Legacy 2117's they are the winners. Ended up at 29.5 inches with 200 grain points, shoot great. I four fletched them with 4" parabolic trueflights.

Congrats on a good choice that'll put your shaft and point weight around 555 grains, and if any of the big box store have aluminum shafts it'll usually be 2117's.

My total arrow weight with the 200gr points and the four Fletch 4" feathers is 593gr, did the math and its running at 16% FOC.