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I'm mostly interested in how they're classified and what that really means. I see 300's, 340's, 400's, etc. What do those numbers mean?

I also see that the gpi seems to go down as the arrow size goes up. This confuses me. Why is that? I would think a bigger arrow, i.e. 400>300 would have more gpi than the smaller one.

Anyone got a link to some details that I could read.

Also, whenever I get around to ordering a new bow (my 7y.o Reflex isn't worth investing effort into), I'd like to make it as well setup as possible. It's main purpose will be the slaying of Ohio's Whitetail population. If I were looking for an arrow that will carrry the most KE, how would I find that? Obviously too light would be no good, yet too heavy would be bad as well. I'm sure there's a happy medium in there that takes into account arrow speed and weight. Is there a chart or some calculator out there that sorts this out?

Say I punch in that my bow will sling a 410gr arrow @ 285fps; will it calculate what it will do with a 350gr arrow, as well as the KE it'd have?


Thanks.
 

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The numbers you put forth are not arrow sizes/weights, but spine. Spine number reflect strength. ONLY the bigger the number the weaker the spine and as such, the lighter the arrow (GPI). This not true of every arrow manufacturer so check thoroughly.
Roughly; A 400 spine would take care of a 60 pound bow and a 340 would handle a 70 pound bow. BUT arrow length and point weight are the two biggest factors that effect spine.
Arrow weight for taking whitetail deer can a be a personal thing. I've known 300 gr arrows to put the hammer on them and get complete pass throughs. Generally, 350 grs is considered about minimal.

There is calculation chart floating around and I may have the source in my files, somewhere. There is also a formula for KE (I use the one from my rifle and pistol days). ??? Maybe this is it - enter numbers and each opens up. http://www.backcountrybowhunting.com/articles/tools.php

Mine;
Mass weight (arrow in grains) / 225218 x V x V / 2 = ft lbs. (KE)

Again, roughly, your given specs; Your 410 gr arrow generates 73.9 ft lbs.
Your 350 gr arrow would increase velocity around 20 fps. So 72.3 ft lbs. Of course the either arrow would well get the job done, but the heavier would have the better momentum.
 

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The search function revealed nothing...

I'm mostly interested in how they're classified and what that really means. I see 300's, 340's, 400's, etc. What do those numbers mean?

I also see that the gpi seems to go down as the arrow size goes up. This confuses me. Why is that? I would think a bigger arrow, i.e. 400>300 would have more gpi than the smaller one.

Anyone got a link to some details that I could read.

Also, whenever I get around to ordering a new bow (my 7y.o Reflex isn't worth investing effort into), I'd like to make it as well setup as possible. It's main purpose will be the slaying of Ohio's Whitetail population. If I were looking for an arrow that will carrry the most KE, how would I find that? Obviously too light would be no good, yet too heavy would be bad as well. I'm sure there's a happy medium in there that takes into account arrow speed and weight. Is there a chart or some calculator out there that sorts this out?

Say I punch in that my bow will sling a 410gr arrow @ 285fps; will it calculate what it will do with a 350gr arrow, as well as the KE it'd have?


Thanks.
DANg sonny you beat me to it, lol, gotta learn to type,lol

the 300, 340,400 numbers you are refering to is spine designation, the weights in relation to spine can be confusing cause they can be what ever the manufactor wants them to be. A 300 spine arrow has .300" of movement with an arrow set on posts set at 28" apart and a 1.94lb weight hanging from the middle of the arrow, the arrow will sag the .300" so that arrow is a stiff arrow. A 400 spine arrow has .400" of sag so not as stiff, you dig, Weights usually you will have a 300 weight more than a 400 in most cases unless it is a special light weight arrow. And some arrow manufactors have numbers that have nothing to do with spine, like Carbon Express usues their own method say a 250CX is close to a .400" spine Easton and a 150CX is close to a .500" spine Easton
 

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arrow

I don't see why you think your bow is not good enough but you didn't ask me for money for a new one so I guess thats not my business,but I know of lots of bows that age and older that still work just fine. In fact my cousin has a Darton much older and kills more deer than most with new high dollar rigs.
Anyway, about the arrow, you can go to Hunters Friend.com and learn a lot about it or just do lots of reading on here and you will figure it out soon enough.
If you tell us about your draw length and draw weight you will get lots of good suggestions including mine. I do tons of experimentation with arrows. You will be sure to get the right arrow for your setup that way.Also as you search you will begin to understand all those confusing numbers which are not as confusing as it seems. Really!!!!!
 
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