A Terrible Tuning Dilemma

[NYRON]

Okay, I'm no slouch when it comes to setting up and tuning bows, but I need some help on this one. I have a 3 piece Thunderhorn longbow with two sets of limbs made with identical woods. One set is 53# @ 28" and the other is 54# @ 27." I'm right-handed and draw an honest 27," shooting 3 fingers under with a glove.

The 54# @ 27" limbs shoot a variety of arrows well, with 29" Beman ICS 400s with 250 grains up front flying the best and hitting right where I look.

The 53# @ 28" limbs, on the other hand, have proven to be incorrigible. Here is what I have tried:

very old 29" GT 3555 Hunter graphites w/ 245 grains up front fly great and hit where I look, but these shafts are no longer available and I only have 3 left

29" Beman ICS 500s w/ 150-325 grains up front . These fly fairly well, but hit erratically with a high percentage of left hits, indicating a too stiff shaft no matter the point weight

29" Beman ICS 400s w/ 245-350 grains up front. These actually fly better than the 500s, but consistently hit 4-5 inches to the left at 20 yards.

29" Vapor Carbonwood 3000s with 150-325 grains up front. Fairly good flight, but hit well left of point of aim and lots of shots with erratic hits.

29" CX Heritage 150s w/ 150-300 grains up front. Goofy, unpredictable flight no matter what I do.

29" CX Heritage 250s w/ 245-325 grains up front. Fly pretty well, but hit far to the left of my point of aim

29" GT 3555 Traditionals w/ 245-325 grains up front. Act just like the CX 150s.

The Beman 400s and CX 250s are clearly over spined. The other shafts act like they are over spined, but according to the fancy shmancy dynamic arrow spine calculator they are really under spined. As you can probably tell, I like all my arrows to be 29, " so I was attempting to tune the set up with this arrow length, but perhaps I need to experiment with different arrow lengths to find the right combination. I can usually do this with point weight alone, but it's not working here.

Two shafts I have considered, but not tried are the CX Predator IIs in 3050 spine and the CX Heritage 90s.

Any advice would be much appreciated.

Thanks,
Ron

[Jeremy]

Those limbs are ~4# lighter than the other set at your draw length.  If adding 50gr to the point weight of your current arrows didn't bring them in tune then something else is at work here (limb alignment issues, tiller, # marked wrong, etc)

One thing that is often overlooked is the effect bow #age has on your release.  I get a much cleaner release with heavier bows.  When I get down to below 40# the string doesn't leave my fingers cleanly and consistency goes to he**.

[trapperDave]

shoot longer arrows. Carbons can be picky, and get more so the shorter they get. Ive found I can get away with more variations on longer shafts(30" or more) I too draw 27