Draw weight and FPS

Duckbutter48 · 10-02-2007, 07:17 PM

How much of a difference does the draw weight mean in FPS. I understand its faster with a heavier pull but buy how much?

EX. If you had a 60-70lbs bow set to 60lbs and shot 280fps what would the difference be with the same bow set at 70lbs and everything else the same. Is there a formula to figure it out or does it depend on the bow?

Arthur P · 10-02-2007, 07:25 PM

I think the rule of thumb is something like 1 fps for every 2 lbs of additional draw weight. So you'd be looking at 285 fps instead of 280. Not hardly worth the extra strain to tug the additional 10 pounds.

bighorns35 · 10-02-2007, 07:58 PM

you also have to put your draw length in there too. a bow advertised to shoot 300fps. is when it is at max weight and max draw. even tho the bow is at max weight,but not at max draw it wont shoot 300. not exactly sure what the rule of thumb is for figuring it out. just thoughts to ponder.

BGfisher · 10-02-2007, 08:02 PM

Close arthur, but no cigar. It's 2 fps for each pound of increase in draw weight. BUT, this only holds true if you're able to shoot the same arrow. If shooting a properly spined arrow for 60# you'd probably have to shoot a proportionately stiffer spined and heavier arrow at 70#. So, keeping arrow weight proportional to draw weight there isn't much difference between 60# and 70# in speed.

SouthDakotaHunter · 10-02-2007, 08:19 PM

Depends on a lot of factors.... For example I have a bow that's about 5 years old and at 63 lbs it's shooting around 245 FPS. My other bow (about 2 years old) also shoots right around 245 FPS but I'm only pulling 53 lbs (with a significantly longer arrow).

bayfire300 · 10-02-2007, 08:32 PM

IBO ratings are 30" draw w/ 350 grain arrow.standard.now if i had a 30" draw w/ a 375 grain arrow i'd be slower in arrow speed naturally............but alot more comes into play here.......like whats on your string.nocks?.....silencers?...loops? all that will decrease your arrow speed.
i ahppen to shoot a 2003 bowtech mighty mite....28" draw 80% let off not to sure od actually arrow weight but around 370. i have nothing on my string bu a loop and 2 leaches( i use the hind sight) and i chrony at 285......if i switch to the 65% let off module i shoot 295...not bad for a short draw. but i find it better for my shoulder and acuracy w/ the 80%.
lets not forget arrow spine...the arrows i shoot for 70#'s are to stiff for a 60# bow.it's all respective.but if you keep the same arrows(hopefully properly spined)and crank up your bow to max.it will be faster....in theory.like i said there are other variables

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