Some help understanding arrow weight

so i need alittle help understanding grains and arrow weight.

I’ve been reading mostly you should use high 300’s - 400 grain arrows for white tails and bigger.

Now I have 340 grain bemas bowhunters. With a 100 grain muzzy broad head. Would this mean that my arrow weight is 440?

Or when people say you should have at least high 3s and up does that mean just the arrow and not the broad head included? Should I buy 400 grain arrows?

Sorry just confused. Thank you

 

The weight of the arrow is determined by how heavy it is in terms of grains per inch (GPI) and then how long the shaft is. Take that and add in all of your accessories like the insert, broadhead/field tip, vanes, arrow wrap, nock, etc to get the total weight.

What you're looking at when you see the 340 is the arrow's spine - or how stiff it is. Generally speaking the longer your arrow shaft is (longer your draw length) and more poundage you shoot you'll need a stiffer spined arrow. Additionally the stiffer the spine the heavier the arrow - generally speaking. A 400 spine arrow will be weaker, and thus lighter, than a 340 spine in the same model.

So looking at your Beman Bowhunter 340 that weighs 9.3 grains per inch. Let's assume you're shooting a 28" arrow that puts your arrow at 260.4 grains before accessories. A standard Beman insert is around 21 grains, standard 100 grain broadhead, 13 grain nock (not lighted) and 20 grains for fletchings (assuming 3 Blazer vanes, no wrap). That would put your arrow right around 415 total grains which is plenty of whitetail hunting.

 

Here's a good article on arrow spine - https://www.bowhunting.com/bowhunt101/arrow-spine/

 

Next is FOC. for good flight.

 

Thank you guys!

I have a 29 inch draw. 70 pounds on triax

I think I am going to give the gold tip hunter xt 340s a try.

 

Just an FYI the GT Hunter 340's are 8.9 gpi so just a touch lighter than your Beman ICS Bowhunters. Shouldn't affect things too much but just something to take note of, especially if you're wanting to go heavier instead of lighter.

 

I did notice they are lighter and did concern me.

I am shooting a new triax this time. Those bemans I was using on my bear bow.

As long as I am over 400gram total I’ll be happy. I hope the set up makes it over 400g

 

Maybe I’ll check out the “ Easton axis black “ arrows. They look to be alittle heavier

 

You should get a .300 spine with those specs. You're likely going to realize that 400 grains is still pretty light for hunting purposes and a 340 won't handle more than a 100gn point at 70#/29" out of that bow. At least, not very well. A .300 spine will give you flexibility to experiment.

 

Really? You think I should go to a .300? I am worried about losing speed. But then again I’ve only been bow hunting a couple years you guys would know more then me.

 

Speed is only useful to get your arrow from point A to b. momentum is what matters for a hunting Arrow because that's what does the work after impact. The more weight you add the more energy you absorb from the bow and the more momentum you have as a driving force.you also retain more speed down range with a heavier arrow than you do with a lighter one. Another thing that happens when you only look at speed is the fact that in the formula to resistance which is what occurs after impact speed is squared. That means a faster Arrow stops faster then a slower one assuming it has the momentum to drive forward which is where the weight comes into play.

This is getting a little complicated for just a spine recommendation but it all ties in.

 

yes. use a 300 spine. Spine does not really affect weight it is the stiffness not the weight. Your Triax is a little faster than my bow per IBO, and I am shooting about 280fps with a 500 grain set up on 300 spine arrows. If I was back down to say 430 grain total weight, regardless of spine, I would be right at about 300fps.

You have a very fast bow, are shooting heavy poundage, and have a long draw. Like me. Going off my arrow manufacturer's website chart, I need a 300 spine.

 

Thank you guys for all your help!

I will look into heavier arrows.

 

A 300 spine I'm with a 150 grain point and steel insert would serve you very well on any animal. That would be my recommendation.

 

Thank you. I currently have 100 grain muzzy 4 blades. You would recommend moving up to heavier broad heads as well?

 

Yes. Look for a solid cut on contact two blade. If the blades break or bend it it could mean game over. Don't get me wrong muzzy is good and four blades is actually better than 3 in my opinion but to is even better and thin blades just don't give you the reliability then a good thick one will.

 

So more of a rage mechanical type ?

 

Lol no. Look up Zwickey or Magnus.

 

now I think we are being trolled.

 

Good thread. I'm just getting into building my own arrows and it's been very fun to learn about these things. One of my winter projects is to really dial this in.

Good advice given so far to the OP.