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Discussion Starter #1
Let me preface this by saying that I've been out of archery for years and am just now getting back into it. So take it easy on me.

I shot a blacked out '09 Alphamax 32 today and ended up deciding it shot too good to not get it. It was set at 28.5 draw and 70 lbs. The arrows I used were just some spares the archery shop had for testing out bows. I just found one that fit the draw length and off I went. Now, I'm only familiar with aluminum arrows and the only grain we kept up with was the grain of the field tip/broadhead. I have no idea what grain tip was on the arrow or what type of arrow it was...it had a wrap, so I didn't see any details. It was definitely thinner than the old aluminum eastons I used to shoot. All of this is relevant because I decided to chrono the bow. It read 343 fps. I'm not sure what IBO is, but I'm pretty sure the arrow I used was below IBO (I've heard some say that...I'm just guessing the arrow was below the standard for that bow).

My first question is: what is IBO? My second question: what type of arrow would produce such a fast reading on a bow that I'm betting should be shooting more around 310 fps at 70 lbs. and 28.5"?

Thanks. I just trying to get back up to speed and this is a situation I could learn a lot from.
 

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Just checked and IBO is 350 grain arrow 30 inches DL @ 70 pounds.


Hoyt says the AM 32 is rated at 321
 

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I am getting 299-300 fps from my 09 AM32 with a Goldtip XT Hunter, 28.5 inches, 403 total grains, 29 inch draw at 70 pounds
 

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I would question the accuracy of the chrono used. 343 is extremely high, especially at a 28.5" draw length. I shoot the same bow at 28.5 DL, 67 lbs. & getting 292 from 377 gr. arrow and 309 from a 335 gr. arrow.
 

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I'll add to the madness.... How does draw length influence IBO?
The draw length influences speed, the IBO is the speed that is put on the bow at the shop.
 

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your chrono is OFF...

I had my AM32 supertuned + custom strings/cables by one of the BEST bow technicians in Central Ohio...PM me if you are interested..


#70.2 @27.5"

350 gr. arrow at 314 fps.

381 gr. arrow at 304 fps.

puts the IBO at 339 fps.......way over what Hoyt spec's...a lot of guys don't believe it until they read the CHRONO!!


 

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Discussion Starter #8
I had wondered if it was off. All I could go by was my old MagnaTec with the old aluminum arrows that shot 270 fps and the Alphamax was blazing in comparison. I had assumed that I was shooting an arrow that was way too light, but I could see the chrono being off. I had also just turned the chrono on and plugged in the bulb for it, so I'm not sure if that would have an effect. I would be happy if I had it a hair over 300 fps for hunting. Any good arrow/tip combos that should hit the mark with the current set-up? I always figure that I could get some slightly heavier arrows if I decide to get into some of the local 3-D shoot where bows have to be under 300 fps.
 
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