Archery Talk Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
792 Posts
Discussion Starter #1
Say I'm shooting a 350 grain arrow @ 70# 30"draw (IBO). Will it still shot it's IBO speed 60#and 300 grain arrow?
 

·
Registered
Joined
·
1,284 Posts
I don't remember the exact number that you lose but it does lose a little bit going from 70 down to 60
 

·
Registered
Joined
·
3,336 Posts

·
OEF VI VET
Joined
·
6,681 Posts
Does this hold true from 60# going down to 50#?
Generally yes, another 3 fps slower at 50# when grained out (250 grain arrows)...so 6 fps slower than ibo

...but keep in mind that a lot of manufacturer's bows come in around 10 fps slower than they are rated to begin with, while some exceed their ratings. Tuning can also affect the speed of a bow quite a bit.
 

·
Registered
Joined
·
3,336 Posts
Generally yes, another 3 fps slower at 50# when grained out (250 grain arrows)...so 6 fps slower than ibo

...but keep in mind that a lot of manufacturer's bows come in around 10 fps slower than they are rated to begin with, while some exceed their ratings. Tuning can also affect the speed of a bow quite a bit.
OK, thanks. From what I've heard at least about my Experience, it is typically right on IBO or faster.
 

·
Registered
Joined
·
931 Posts
Unless its maxed out at 60 then you dont lose any performance. Mine maxed out at 63.5 is actually over ibo.
 
Joined
·
9,026 Posts
I don't remember the exact number that you lose but it does lose a little bit going from 70 down to 60
Not quite sure what you are missing here...you will lose approximately 2 fps per pound of draw weight that is drop so going from 70 to 60 should theoretically give you a 20 pound decrease. For the other part of the question, the bow should shoot it's IBO at 60 with a 300 grain arrow...theoretically. Also, don't forget to subtract for the peep and other additions to the bowstring...take away 1 fps per every 3 grains...approximately. Cheers!
Fred
 

·
Registered
Joined
·
903 Posts
I've shot a 350grn arrow at 70lbs at a speed of 305 and a 300grn arrow at 60lbs at the same speed. This was with my AM32. I would assume different bows would yield different results though.
 
Joined
·
9,026 Posts
Elite Archery says to deduct 2-3 fps for 60# vs 70# Is that per pound? There's no way its only 2-3 fps from 60 to 70lbs
Has to be per pound...cannot even imagine going from 70 to 60 and only losing 2-3 fps with the same arrow...that would be phenomenal! Cheers!
Fred
 

·
Registered
Joined
·
3,299 Posts
fps is similar but, kinetic energy is a lot less, lighter arrow at same speed has less kinetic energy
 

·
Registered
Joined
·
127 Posts
Some one would need to test that situation.
 

·
Registered
Joined
·
194 Posts
Elite Archery says to deduct 2-3 fps for 60# vs 70# Is that per pound? There's no way its only 2-3 fps from 60 to 70lbs
That is for determining speed at 5 grains per lb. You would lose 2-3 fps on a 60lb bow shooting a 300 grain arrow versus a 70lb bow shooting a 350 grain arrow at the same draw length.
 

·
Registered
Joined
·
1,112 Posts
No they are talking if you are shooting a 5gr per pound arrow at 70 (350) vs a 5 gr per pound arrow at 60(250). The 60 # bow will be about 3fps slower even though it is shooting the same 5 gr per pound. The heavy draw weight is more efficient at overcoming friction and thus you see less speed loss. They don't mean 2-3 fps loss for 10 lbs. They mean 2-3 fps loss in IBO rating in a 60 lb bow vs 70.

Sent from my EVO using Tapatalk 2
This is correct! Lighten the lbs you lighten the arrow also to get your IBO speeds
 

·
Registered
Joined
·
931 Posts
Just because your bow maxes above advertised draw weight doesnt mean it is exceeding its IBO rating.

Sent from my EVO using Tapatalk 2
I didnt say thats why it was. At the speed im getting it is going approx 1 or 2 fps faster than IBO.
 
1 - 17 of 17 Posts
Top