There must be a flaw in the program. I thought it was kind of funny that a 5000 series had a spine of 0.300. Usually the higher to number the weaker the spine. Atleast this is true for easton arrows. A 500 series has a spine of 0.500 and a 340 has a spine of 0.340. Any way according to OT2 with 72# draw weight your optimum arrow spine should be around0.4525 if the prgram is correct which i believe it probably is. If the arrow you are using is close to that spine you should be ok but even when i enter the 3000 (0.400 spine) series arrow it still showed your spine pretty stiff for the length of arrow. I would probably trust the blackhawk website spine rating and as long as they say it is right then you should be ok. Sorry for any misinformation i am not familiar with this prticular arrow and just trusting the program to have the right numbers.