I have several but the one in question is a Browning Boss Tracker: Contour XP limbs, Heat Cams, 65% let-off 8in Brace height, 42in axle to axle and the draw length is 31-33in. There are no cam replacements you just move an allen screw to change the draw length in 1/2in increments so this is the only range for this bow. The actual listed IBO is 287 (I think) I rounded up for ease of discussion. It is set up with a Cobra Venom sight, Wisker Bisquit rest, True Glow stabilizer, cat wiskers, two tied on nocks with a string loop, Surz-A-Peep (three strand kind) a Bohning Lynx 4 arrow quiver and it's about 3-4 years old.

I'm not a speed freak and this is actually my fastest bow LOL I was just wondering as to how they came up with an IBO number for my bow. (or for any bow that starts over 30in for that matter)

I am not sure but I believe Browning also made this bow in a shorter draw range. Could it be that they just tested the shorter range bow (30in) and used that IBO speed fot this one as well?

I don't know, this has been a question I have had for a while and I thought I would post the question.