arrow speed

[petew]

Originally Posted by CBintheNorth

Funny that they're going with a 'more strict' set of guide lines

Anyone remember why they did away with AMO speeds?

IBO speeds are faster and sell more bows.

[L.O.S.T.Arrow]

Originally Posted by petew

IBO speeds are faster and sell more bows.

Pretty much Correct...
Back in the day all bowhunters were 29" draw 70 lb pull....lol

AMO tests/rating was done at 60 lbs....IBO was done with lighter arrow at 70lbs...Same bow same speed but with IBO rating is so much faster...so everyone wants that really fast bow...

To Quote Archery Exchange-

A.M.O.(Archery Manufacturing Organization) and I.B.O. (International Bowhunters Association) both have a method for testing arrow speed from bows and although they are different both can be used to compare equipment for relative speed.

Both of the speed testing standards use a constant drawlength, arrow weight and bow weight to test bowspeed. These are the way the two differ.

A.M.O.

Under this standard the bow being tested will have a maximum pull weight of 60lbs. The arrow will have a grain weight of 540(9 grains of arrow weight per pound of bow weight). The draw length will be set at 30 inches. The chronograph used for measuring the speed will be placed at point blank range for testing.

I.B.O.

Under this standard the bow being tested will have a maximum pull weight of 70lbs. The arrow will have a grain weight of 350(5 grains of arrow weight per pound of bow weight). The draw length will be set at 30 inches. The chronograph used for measuring the speed will be placed at point blank range for testing.

What is important about these two speed ratings is that they are only to be used to compare bows speed tested under the same standard. They should NOT be used to tell you what you will personally shoot for speed. For example lets take an average archer……Bill Bowshooter……..Bill has a 29 inch draw length shoots his bow at 65 lbs and shoots a 455 grain aluminum arrow. In our example neither the A.M.O. or the I.B.O standards will accurately reflect the speed of Bill’s bow. Since Bill is shooting a shorter draw than both standards, shooting an arrow that weighs 7 grains of arrow weight per pound of bow weight, and is shooting 65 lb peak weight he will shoot at a speed very different to either standard.

If we try to make some generalizations about the two different ratings we could say that the I.B.O. speed rating is much faster than most archers could achieve, and conversely the A.M.O. speed rating reflects a speed that is less than what most shooters could achieve with the same bow. If a bows I.B.O. speed rating is 320fps and its A.M.O. speed rating is 245fps that would mean the average archer would shoot that bow somewhere in the middle of that range.


Neil

[Lefty-Canuck]

Proof is in the pudding...set your bow up and chrony it.

LC

[L.O.S.T.Arrow]

Originally Posted by Lefty-Canuck

Proof is in the pudding...set your bow up and chrony it.

LC

OR sit back eat your puddin...and know that bow is fast enough to take down anything your hunting...and its a heck of a lot faster than your last bow...

Any old Chrony can tell you that you wont hit that critter at 340 feet in that second anyway and making your bow shoot 3 more feet in that second aint gonna matter either...Just make you miss that much faster....lol

Here is my Old Chrony Graph





lol

Neil

[bowshot]

Has anybody figured out the time of flight to target difference between these "slow" arrow speeds of 270 fps and the acceptable speeds of 300+ fps? If you figure that out and convert it to inches of arrow in the target at 20 or 30 yards, the 300 fps + arrow will be in the target about 10" by the time the slow arrow hits. Remember that both are still travelling at about 2840 inches to 3600 inches per second. flight time at 20 yards will be about 1/4 second. The difference is pretty small in real life.

Terry

[Lefty-Canuck]

I like to know how quick my setups are so if anyone asks me how quick, I can answer honestly.....instead of saying "real fast" or "faster than my old bow" or "it IBO's at 350 so I should be right around there."

LC

[L.O.S.T.Arrow]

Originally Posted by Lefty-Canuck

I like to know how quick my setups are so if anyone asks me how quick, I can answer honestly.....instead of saying "real fast" or "faster than my old bow" or "it IBO's at 350 so I should be right around there."

LC

Ya butt yer Anal!!!

LOL



Neil

[Lefty-Canuck]

Originally Posted by L.O.S.T.Arrow

Ya butt yer Anal!!!

LOL



Neil

I prefer to say particular

LC

[CBintheNorth]

Originally Posted by petew

IBO speeds are faster and sell more bows.

I was being sarcastic, but yes, that is correct
In my opinion, AMO speeds were closer to what most could achieve, without rattling their bows apart.
Bows nowadays can handle much lighter arrows, but who shoots 350 grs?
Neil would know better, but I would say that most archers draw 60-65 lbs and shoot 400-450 grains.
God forbid the rating system used those numbers for a base-line.

[L.O.S.T.Arrow]

Originally Posted by CBintheNorth

I was being sarcastic, but yes, that is correct
In my opinion, AMO speeds were closer to what most could achieve, without rattling their bows apart.
Bows nowadays can handle much lighter arrows, but who shoots 350 grs?
Neil would know better, but I would say that most archers draw 60-65 lbs and shoot 400-450 grains.
God forbid the rating system used those numbers for a base-line.

Bang on!!!

Neil

[Cofirearms]

Originally Posted by L.O.S.T.Arrow

Bang on!!!

Neil

So i shoot 250gr arrows with 100gr broad heads. Is that too light? My draw is 27.5" at 60lbs.

[Lefty-Canuck]

Originally Posted by Cofirearms

So i shoot 250gr arrows with 100gr broad heads. Is that too light? My draw is 27.5" at 60lbs.

250gr arrows PLUS 100gr broadheads is a 350gr arrow.

LC

[Cofirearms]

Originally Posted by Lefty-Canuck

250gr arrows PLUS 100gr broadheads is a 350gr arrow.

LC

Yes I know that haha, I was wondering because CB said that most shoot 400-450. I am a really big gun guy but am new to the bow world, in my dictionary weight depends on the game hunted, so I'm going after Muley and elk this fall.

[Lefty-Canuck]

Originally Posted by Cofirearms

Yes I know that haha, I was wondering because CB said that most shoot 400-450. I am a really big gun guy but am new to the bow world, in my dictionary weight depends on the game hunted, so I'm going after Muley and elk this fall.

I hunt with a 385gr arrow....it has never let me down.

LC

[CBintheNorth]

Originally Posted by Cofirearms

Yes I know that haha, I was wondering because CB said that most shoot 400-450. I am a really big gun guy but am new to the bow world, in my dictionary weight depends on the game hunted, so I'm going after Muley and elk this fall.

Unfortunately, it's not that simple.
The biggest question is, are they spined properly for your bow and setup?

[kujoseto]

Originally Posted by Lefty-Canuck

I hunt with a 385gr arrow....it has never let me down.

LC

What draw weight are you using with that arrow? What broadhead weight? What arrow is it? (Just curious)
I'm using 125gr bh and would need to use a much lighter arrow to get sub 400gr. My arrows are 9.3 gpi and total weight around 450 I think. Shooting 72 lbs experience.
I don't feel the need to go faster, but it's always intriguing.

[Lefty-Canuck]

Originally Posted by kujoseto

What draw weight are you using with that arrow? What broadhead weight? What arrow is it? (Just curious)
I'm using 125gr bh and would need to use a much lighter arrow to get sub 400gr. My arrows are 9.3 gpi and total weight around 450 I think. Shooting 72 lbs experience.
I don't feel the need to go faster, but it's always intriguing.

Goldtip HunterXT Pro, 7595 (340). 70 lbs Bowtech Invasion @28 inches, 100gr Grim Reaper Razor Tip.

LC

[Cofirearms]

Originally Posted by CBintheNorth

Unfortunately, it's not that simple.
The biggest question is, are they spined properly for your bow and setup?

I'm shooting a Mathews Z7 with a 27.5" draw at 60lbs. For arrows I'm using 250gr carbon express mutiny slashers, they have a spine of 0.392. I'm not sure if this information would help or not?

[kujoseto]

Thanks LC
The way you take down elk is a testament to not needing the heavy set up. I don't know that I'd bother changing, but it's nice to know that if I do, I don't need to be concerned about weight as much as being properly spined and tuned

[Lefty-Canuck]

Originally Posted by kujoseto

Thanks LC
The way you take down elk is a testament to not needing the heavy set up. I don't know that I'd bother changing, but it's nice to know that if I do, I don't need to be concerned about weight as much as being properly spined and tuned

Farthest I have shot is 35yards closest is 15yards....all passed through.

LC

[kujoseto]

Well I put a chrono on the front of my bow today and I clocked 4 arrows. 3 at 277 and 1 at 275. I think I'm running 442gr (less sure on this mass than the other specs) from a Bowtech Experience (ibo 335) at 72 lbs and 29" so I was anticipating 285-290 based on some online calculators. Bow is tuned and... dare I say, has a whisker biscuit. Anyone find discrepancies from online calculator and real world measurements?

[L.O.S.T.Arrow]

Originally Posted by kujoseto

Well I put a chrono on the front of my bow today and I clocked 4 arrows. 3 at 277 and 1 at 275. I think I'm running 442gr (less sure on this mass than the other specs) from a Bowtech Experience (ibo 335) at 72 lbs and 29" so I was anticipating 285-290 based on some online calculators. Bow is tuned and... dare I say, has a whisker biscuit. Anyone find discrepancies from online calculator and real world measurements?

Wow that does seem a little slow huh...not getting into the WB topic ..giving a few feet per second loss...

Was fast enough until you put in on the chrony huh...lol

The online Calculators are at best a "Guess-timate" and based on Manufacturers sloopy IBO's...HOWEVER...

…Based on rated IBO…
IBO speeds are based on a bow with a 30" draw set at 70lbs shooting a 350gr arrow.
-For every inch of draw length you go down you will lose 10 FPS
-For every 5# draw weight you go down you will lose 10 FPS
-For every 3 grains of weight your arrow is over IBO ( 5 grains per pound) you will lose 1 FPS
-For every 3 grains of weight you add to your string you will lose 1 FPS

-Minus 10 FPS for your Draw
-Minus FPS for Arrow >442-350=92gr...divided by 3 =30.6 FPS
-Minus being generous on weight>5-8gr for loop [know your loop=5gr]=2FPS
-Minus being generous on weight> 6 Gr G5 1/4 Peep=2FPS
[1/8" Target Peep- 4.5 grains
3/16" Hunter Peep- 5 grains
1/4 Hunter Peep- 6 grains]
-Minus Even 5FPS for WB [which would be erased by bow being 72 LBS]

Totaled 49.6 FPS loss...

IBO 335-49.6=283.4FPS
285.4 FPS - WB 5FPS if calculated =280.4

This Calculation is only 8.4 FPS [WB 3.4] from your actual rating...

So very close in plus or minus FPS [ on sloopy IBO Ratings]

Your big FPS loss is arrow weight...and poundage @ 10 FPS

Now take that same bow and drop draw to 28" like myself = minus an extra 10FPS...it may depress some...

IMHO unless your a "have to know shooter" that works to the point of anal on bows...[many of us out there] ...then most times it actually better NOT to know your actual Chrony rating of your favorite bow...

If it was fast to you before rating it...it is NOT any slower once you know actual Chony speed...lol

Neil

[kujoseto]

Haha yes my bow is WAY slower now lol.
I have absolutely no issue with the speed, (if I wanted speed, I wouldn't own a 335 ibo bow) I just had hoped the online calculator I was using was accurate. I guess it is still being generous considering what you calculated was closer. If you throw in a miniscule % loss to efficiency in transfer of energy, you're incredibly close.
I still think my arrows are moving much faster than necessary and I'm not about to change anything. I also think it was interesting that 3 arrows were identical speed and the other was really close. I have no idea the quality of the chrony either.

BTW, I got some compliments on the strings, despite being the worst colour option lol

[L.O.S.T.Arrow]

Originally Posted by kujoseto

Haha yes my bow is WAY slower now lol.
I have absolutely no issue with the speed, (if I wanted speed, I wouldn't own a 335 ibo bow) I just had hoped the online calculator I was using was accurate. I guess it is still being generous considering what you calculated was closer. If you throw in a miniscule % loss to efficiency in transfer of energy, you're incredibly close.
I still think my arrows are moving much faster than necessary and I'm not about to change anything. I also think it was interesting that 3 arrows were identical speed and the other was really close. I have no idea the quality of the chrony either.

BTW, I got some compliments on the strings, despite being the worst colour option lol

hahaha...on string color...at least no one is gonna steal it...lol

[Diamondhitch]

Havent read all the posts but when I started bowhunting 200-230fps AMO (before IBO lol) was smoking fast and we killed plenty! Moose at 50yds no prob. Bows older and slower did well too. Recurves and longbows... you guessed it - kill em dead to this day. Any legal modern bow TUNED to shoot true will not only kill anything on the continent, it will take a few years off the tree behind it as well..