What is the difference between these two arrow speed ratings? I have heard a little, but not sure what the standards are. Also, is there a formula for figuring each different bow without using a chronograph? For instance, I am about a 27 1/2" draw at about 60#. If I am using a bow that is rated 320 IBO, what should I expect my arrow speed to be? Thanks for any help.
A.M.O. Under this standard the bow being tested will have a maximum pull weight of 60lbs. The arrow will have a grain weight of 540(9 grains of arrow weight per pound of bow weight). The draw length will be set at 30 inches. I.B.O. Under this standard the bow being tested will have a maximum pull weight of 70lbs. The arrow will have a grain weight of 350(5 grains of arrow weight per pound of bow weight). The draw length will be set at 30 inches.
For the ATA Rating the industry uses a 30 inch draw, 60# bow shooting a 540 grain arrow , Its the same thing as A.M.O
Would the fps drop that much? Wow...thanks guys. I was not aware of the AMO...I had just been doing some looking online at the BassPro website and seen ATA.
Those tests are done with nothing on the string (loops,knocks,silencers etc.)and no fletching on the arrow all of which will slow down your arrow which will probably be heavier also, I would think the average hunting arrow would weigh around 365 to 400 grains. Your draw length being 2 1/2" shorter also is slowing the bow down. I wouldnt worry about it too much 250fps is plenty fast.
