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A.M.O.(Archery Manufacturing Organization) and I.B.O.
(International Bowhunters Association) both have a method for testing
arrow speed from bows and although they are different both can be used to
compare equipment for relative speed.
Both of the speed testing standards use a constant drawlength, arrow weight and bow weight to test bowspeed. These are the way the two differ. 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. The chronograph used for measuring the speed will be placed at point blank range for testing. 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. The chronograph used for measuring the speed will be placed at point blank range for testing. What is important about these two speed ratings is that they are only to be used to compare bows speed tested under the same standard. They should NOT be used to tell you what you will personally shoot for speed. For example lets take an average archer……Bill Bowshooter……..Bill has a 29 inch draw length shoots his bow at 65 lbs and shoots a 455 grain aluminum arrow. In our example neither the A.M.O. or the I.B.O standards will accurately reflect the speed of Bill’s bow. Since Bill is shooting a shorter draw than both standards, shooting an arrow that weighs 7 grains of arrow weight per pound of bow weight, and is shooting 65 lb peak weight he will shoot at a speed very different to either standard. If we try to make some generalizations about the two different ratings we could say that the I.B.O. speed rating is much faster than most archers could achieve, and conversely the A.M.O. speed rating reflects a speed that is less than what most shooters could achieve with the same bow. If a bows I.B.O. speed rating is 320fps and its A.M.O. speed rating is 245fps that would mean the average archer would shoot that bow somewhere in the middle of that range. |
