For all you techies out there, I' m wondering how much (typically) arrow weight would affect the " advertised" IBO speed of a bow.

For example, if a bow is advertised at 300 fps IBO, using a 350 grain arrow, what would be speed be for an arrow that weighs slightly more than IBO?

How much speed do you lose for every 5 grains of weight above IBO?

Again, just looking for general/ballpark figures.

Thanks,

Jim

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OK, let me be a little more specific.

I' m looking at a Hoyt MT Sport, rated at 290 fps (IBO). I' m assuming that IBO tests bow at 30" draw, 70# wieght, 5gr/lb arrow - correct?

I will be shooting a 385 gr Carbon Express CX 300 out of it at 70#/30" draw. What can I expect the speeds to be?

Thanks again,

Jim.

Like Krisken stated about 7-10 fps with NOTHING else on the string.
Anything you add to the string you have to add that weight also.

v2 = v1 * square root ( m1 / m2) = 290 * sqrt( 350 / 385) = 276.5

This assumes that NOTHING changes save for the weight of the arrow.

Actually the bow will be slightly more efficient with the heavier arrow.