ORIGINAL: GMMAT
Correct me if I'm wrong but I believe they slow your arrow down some too.
They are heavier than regular vanes.
So......we're talking (for my setup in '08) the difference between (hypothetically.....it'll probably be faster[&:]) 300fps and 302fps .......and relating that to 20 yds or less.
Yes. They are heavier. A heavier arrow is a slower arrow. So....you are correct.
I believe it may also have something to do with the drag due to the design of the vane.