# Too Light for Elk?



## polarbear (Aug 1, 2011)

I recently got a new bow and have been playing around with a little lighter set up just for fun. I'm shooting a 371 grain arrow at roughly 300 ft/sec and 74 ft-lbs. 

This is all based on internet archery calculators so take it with a grain of salt.

Anyway, what's your opinion? Is it too light for elk? I've always been from the school of "it's all about shot placement" but I'm sure some would disagree. What do you think?


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## HuntinFoolUtah (Jan 11, 2013)

It will do the job, but I prefer a heavier arrow with a fairly high FOC. I shoot a 494 grain arrow right now and it's traveling at 294 fps. On the general archery hunt this year I finished a buck that a guy had gutshot. At 93 yards my arrow blew through both scapulas, the buck took 3 steps and died.


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## alpinebowman (Sep 24, 2007)

I have killed elk with with a 370 grain arrow. for most of my kills I have been in the 390-395 grain range and have killed elk at 75 yards a few times. And yes placement is certainly key. My brother hit a bull at 30 yards he thought was still at 40 right in the shoulder. I watched through my scope as the arrow literally stopped at the insert. Was he shooting a 370 grain arrow? he wasn't. He was running a 550 grain arrow with some good speed. I never would have thought his penetration would be so minimal. For the smaller game it will help more but I pinned a buck at 45 yards trough both shoulders and the spine with my 390 grain arrows shooting at 285 FPS and zipped through goats at crazy distances but elk are a different breed. unless you get perfectly broadside shoots under 40 yards you aren't going to get too many complete pass through shoots on a big bodied elk IMHO


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## swbuckmaster (Sep 14, 2007)

Polar your shooting 30+ fps faster and a few grains heaver then i am. On a broadside elk you will get a complete pass through out to 40 yards or so if your using fixed blade heads. You hit leg bone on an elk and like alpine says nothing will get through it.

Your set up will almost go through a deer lengthwise with a fixed blade! 

Antelope are like jack rabbits a 30 lb bow will blow through them.


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## polarbear (Aug 1, 2011)

Thanks for the input guys. I don't shoot much past 40 yards anyway, but it sounds like I should definitely trade in my mechanicals for a fixed head and make sure I only take a high percentage shot. I'm still toying with the idea of using my old arrows which are a little over 400 grains, but there is something about a fast arrow and a narrow spread on my yardage pins that I really like. Thanks for the reassurance that it can be done though.


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## bow_dude (Aug 20, 2009)

I can't back any of this up with mathematics, but I can with practical experience, so take it with a grain of salt. Many years ago, I ran into a guy at SL Archery who was a weapons designer for the military. He lived in Park City at the time. He was trying to get an arrow to break the 500 ft per second speed barrier. He shot it from a gun barrel that was pumped full of gas pressure. He was there looking for the correct size of aluminum arrow to snuggly fit the barrel. Any who... our discussion got started talking about broad heads, fixed blade vrs. mechanical, vrs. cut on contact. His comment was one I hadn't thought much about at the time. He said cutting is a function of motion. It doesn't matter how much power you have behind the arrow, what makes it work is motion, not weight. Then we got into the speed discussion. He said that as things increase in speed, the rules change. He noted that bullet resistant vests used to be made of 32 layers of silk. The silk would "absorb" the projectiles energy thus stopping it. Then he said they started shooting faster bullets and the silk would "snap" and the bullet would pass through, so that is when they changed and started making the vests using Kevlar. A slow heavy projectile will hit a bone and if it has enough momentum, will "push" through it. A lighter but faster moving projectile when it hits, will cause the bone to explode. Then he cited examples of how a fast moving light weight projectile will bring down a turbine engine such as a jet engine because it will bounce around and breakup the "fins" while a heavy projectile will simply push through everything, leaving a hole and not do much damage. (Not sure how that one relates to archery) Any way, I have tested what he talked about with light weight, fast moving arrows and have had very good results. I once shot an elk with a mechanical spitfire broad head using an arrow with a total weight of 350 grains. Complete pass through, 30 yard shot and the arrow burried itself 2 inches into the tree it hit. I had another at 45 yards, make a complete pass through length wise shooting 70 lbs and weighing 350 grains with a fixed blade. Three years ago I shot another elk with a 368 grain arrow tipped with a cut on contact broad head at 35 yards, quartering towards me, shot through the front of the elk and passed almost completely through length wise stopping when it hit the off side back hip. My worst penetrating arrow kill on an elk came from a 560 grain arrow with a fixed blade broad head using a 70 lb bow on a broad side shot. I got barely 12 inches of penetration. That bow was probably shooting in the neighbor hood of 225 - 240 fps. The other bows were shooting in excess of 300 fps. This is getting long, but my experience has been that faster moving arrows seem to penetrate great even though they are light by many peoples "standards". In the last 15 years, I have not had an arrow not get a complete pass through on elk, hogs, deer, or antelope. My average arrow weight has and is 265 grains. It is all in shot placement.


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## polarbear (Aug 1, 2011)

Thanks bow dude. The more I think about this, the more it makes sense. I'm sure there's a 9th grade physics formula that would answer all my questions, but for now I feel good about it. After all, natives have been killing stuff with sticks and rocks for thousands of years. I'm pretty sure even the lightest setup in a modern bow is a far more efficient killing machine than a primitive bow and arrow. The other side of the equation is the hunter. I'm pretty sure if I do my part, the arrow will do its part.


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## swbuckmaster (Sep 14, 2007)

Polar I don't buy what bowdude is selling! While I said you have enough ke to kill an elk and get a pass through with your setup. A heavier arrow out of the same bow will penetrate better than a light arrow out of the same bow! It's simple physics once an object is in motion it wants to stay in motion. A heavy object will stay in motion longer. A light object stops faster. A bow is also more efficient in transfering all of its energy to the arrow with a heavier arrow. Proof is in how quit and smoth it is when it's shot with a heavier arrow.

If I had a LE elk tag I'd have a 450-550 or so grain arrow built with more foc. My shots will be close because I would be sitting water. I will use a good sized cut on contact two blade fixed blade broad head with big 4" vanes. 

Arrows are no different then bullets there are hundreds if not thousands of bullets designed for different things just like there are arrows designed for different things. Now will a 338 Lapua kill a rabbit-elephant? Yes! So will a 30" draw pulling a hundred pounds shooting a 1500 grain arrow but you can see one is over kill. Some where in the middle you sacrifice something but may still get the job done with proper shot placment. The closer you match the weapon to the game your hunting the better off you will be!


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## polarbear (Aug 1, 2011)

swbuckmaster said:


> It's simple physics once an object is in motion it wants to stay in motion. A heavy object will stay in motion longer. A light object stops faster.


 I understand this is the case, and I agree. But at what point does speed compensate for lack of mass? There has to be a point where speed makes up for being light where kinetic energy is equal to a slower heavier object. Guess I'm gonna have to dust off the old physics text book.


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## Jmgardner (Sep 17, 2014)

you pretty much stated the formula anyways, polar bear. F=MA. force is mass times acceleration. so the compensation is proportional. if you decrease the weight by half, you have to double the speed to make up for it. so i guess it comes down to how fast can YOUR bow shoot YOUR arrow?


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## polarbear (Aug 1, 2011)

OK. I did some simple calculations. It looks like when comparing my old arrow (413 grains) vs. my new arrow (371 grains) out of the same bow, kinetic energy is about 3% higher with the heavier arrow. However, if I bumped up to say a 500 grain arrow out of the same bow, I'm looking at a 24% increase in kinetic energy. Apparently you can never generate enough speed to compensate for mass out of the same bow. Maybe I should just quit thinking so much and go kill something. Thanks for putting up with me guys. I'm sure this is basic stuff for all you archery pros, but I'm still relatively new at this. You got the wheels turning.


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## HuntinFoolUtah (Jan 11, 2013)

There are a million different ways to skin a cat. Both heavy arrows and light arrows have and will continue to kill animals. The heavier arrow will do it better if you make a less than perfect shot though.


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## c3hammer (Nov 1, 2009)

To muddy the waters a little further, I'll state that none of these arrows in the weights we are talking about matters at all.

The most important factor in penetration on big game, regardless of momentum or kinetic energy is how true the arrow flies. It is imperative that the arrow be perfectly in column to get the full capability of what ever your setup is. An arrow traveling at an angle loses it's energy almost exponentially with angle. Numbers in the neighborhood of 15% loss of energy at only a 2 deg angle have been shown.

Make that thing fly straight into the target and any arrow in the realm we can buy will more than do the job. My set up with 375 grain arrow going 260 fps quartered forward through my 2010 san juan elk and buried 3/4" into the opposite leg bone.

On a side note polarbear, your numbers are most likely incorrect. The difference between a 300 grain arrow and a 500 grain arrow out of any modern compound will show less than a 10% gain in KE with the heavier arrow.

Cheers,
Pete


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## bow_dude (Aug 20, 2009)

The bows of today are so much more efficient than those of years ago. As was stated, where is the point of overkill? I could care less if SW buys what he thinks I am selling... you can't argue with experience. The heavier arrow I was shooting came from an old PSE Phase II bow from the late 70's or early 80's. No doubt that the same arrow from a modern compound bow would do much better today, but the fact remains, it was my worst penetrating arrow on an elk. My point is, with the efficiency of todays modern compounds, I've yet to not penetrate completely a broadside shot with any animal I have shot in the last 15 years, that includes bear, elk, deer, hogs and antelope. Get yourself a computer program that will calculate arrow k.e. at different distances and different weights and different speeds. You will be surprised at the calculated results. I am not advocating that speed will make up all the difference with a lighter arrow, but I am advocating that you can get the results you need with a faster setup when using a light arrow. I use a program called T.A.P. which will calculate all these different setups. I use it for the different species of critter I am hunting. For instance, my antelope arrow is different than my elk arrow, which will be different than my moose arrow (should I ever draw). I want a flat shooting, long distance arrow when hunting lopers. When I sit a tree stand, I like a different arrow again. If I am shooting spots or 3-d, indoor or out door, again, I will make a different arrow. Don't get stuck in a rut and don't be afraid to experiment and learn your equipment. That is what keeps archery interesting.


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## polarbear (Aug 1, 2011)

c3hammer said:


> On a side note polarbear, your numbers are most likely incorrect. The difference between a 300 grain arrow and a 500 grain arrow out of any modern compound will show less than a 10% gain in KE with the heavier arrow.


I wouldn't doubt it. I'm not the sharpest tool in the shed.


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## polarbear (Aug 1, 2011)

Thanks bow dude. I'll have to look into T.A.P.


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