Two questions: Spine and Weight

[bowfiend]

Thanks for humoring another spine question! Most of the bows I have shot are in the same 52-59 lb weight range at 29 inches of draw. I've had good luck shooting some Easton full metal jacket 400's cut to 30" with 100 grain inserts and a 125 grain head. Finishes out at about 550.

Now, I've had the good fortune to pick up a Shawnee with carbon/foam longbow limbs that pulls about 66lbs at my draw and my 400's seem a bit week (keep in mind - a 30" arrow with 225 on the front. I was reading Bob Burton's info (whispering wind arrows) and he's adding significant spine for each inch of arrow above 28", which makes me think I should shoot a 340. I guess I'm having trouble wrapping my head around shooting the same spine as my compound buddies who shoot 70lb wheelies. Does this seem right to you guys?

Second, I've always tried to shoot 10 grain/pound draw, but for no reason other than it just worked for me. Is there any risk of damaging my limbs if I'm only shooting 8.5 grains/pound draw? This thing smokes a 550 grain arrow, so I'm not concerned about losing speed by adding weight, but part of me thinks that I've killed things efficiently (read quickly)with the same arrows at lower speeds so why change it?

Thanks for the responses.

[Don Stokes]

Fiend, traditional bows usually need stiffer arrows than wheel bows, pound for pound. The letoff of a wheel bow softens the acceleration of the arrow, but a traditional bow hits the arrow with everything it has upon the release.

[bowfiend]

Thanls Don. That's kind of counter-intuitive, but definitely would explain why I'm seeing weak on 400's. I guess I knew I needed to go with stiffer spine, but it's always good to get confirmation before spending the money.

Thanks

[crandog]

Yes, but remember your wheelie friends aren't point loading their arrows either.

[bowfiend]

Anyone have a take on the potential limb damage at 8.5 g/lb?

Thanks again for the info.