Yep, I get better results with .600 spine carbons with bows #45 to #55 than I do with stiffer arrows. Bob

I shoot bow poundages from 50 to 58lbs I struggled for several years trying to find a carbon arrow that flew perfect. for some crazy reason I put a 100 grain insert into a 3555 goldtip and I was shooting 175 tips and WOW that thing flew like they say "a dart" I did some experminting and found the CE Heritage did the same these arrows are cut to 30 inches, I did a check on Stu"s Calc and found the goldtips dynamic spine was 32lbs and the CE was 35lbs, what!! this could not be true, but they flew like I have never seen a carbon fly b4, So I have found my arrow and I am glad others are using weaker shafts and getting good results, I believe it to be another discovery about carbon. they recover so quickly from paradox that It appears you can use a supposedly weaker shaft and get good results  ..BTW the goldtips weigh in at 535 grains and the CE 620 so these are not lightweight arrows at all,, good hunting weights

I am a firm believer that you are better off using a shaft that is under spined than one that is over spined. Using the correct spine always is best, but because most shooters do not have perfect form or perfect release, their shafts often shoot stiff.

Whatever tuning method you use. Let the bow tell you what the correct spine of the arrow is. Instead of worrying about being overspined or underspined take some time and get "Just right spined"

Thanks everyone, glad to see I'm in good company. Only reason I asked was because I've spent a bunch of money and time trying to make the "reccomended shafts" work and was pulling what little hair I have left out trying to make them work...

I shoot 2117s from a 60# @ 28" bow that I draw to around 29 1/2" with 200 grains up front.  Badly underspined according to Stu's calculator, but they fly way better than the heavier spined arrows.

Results could be skewed due to how the underspined numbers were achieved. High end EFOC and Ultra-EFOC arrows may dramatically impact arrow flight.

Example:
One arrow set-up with normal FOC that is 30#'S under-spined will likely demonstrate poor flight. Where a 30# under-spined arrow set-up with Ultra-EFOC will demonstrate exceptional flight.

I have several Hill bows that seem to prefer arrows - wood - spined at the bow's stated draw weight.

Yep I shoot 15-35 GT with my 45lb limbs and 35-55 with my 55#, and 58# limbs.  I just had this discussion with Randy Morin at league tonight.  I'm a new convert as of a couple of years ago.

I think for years my tuning problem was overspined shafts.  Alum,wood,and carbon.    

Jeff