Elknut Penetration Test

[tracker12]

Elknut
I remember viewing your penetrations tests a while back as it relates to arrow weight. Can you tell me what bow type and poundage the bow it was done with.

[ElkNut1]

I've used several different ones over the years but my last one was with a Hoyt AM32 65# 27-1/2" draw.

Do you have a specific question in mind about the test? Thanks.

ElkNut1

[sbschindler]

over on the leatherwall there was a discussion about a 43 lb longbow and using a 580 grain arrow I mentioned your penetration tests, I suggested that that he use a arrow wieghing in about 100 grains less , Tracker said your test used a compound bow,, the tests I remember reading and talked to you about were done with a 55 LB longbow, here is the test.

I've done a bit of testing on longbow & recurves with 400grn-500grn-600grn-700grn-arrows all with 2-bladed broadheads & from 150grns to 275grn up front. I shot into layers of 5/16" cement board. I felt the heavier the arrow the more it would penetrate so I wanted to see for myself, this was 3-4 years ago.
I shoot a 55# longbow at 27" so this was one I tested here! To make a long bit of testing short the results were this! The 400grn arrow penetrated as good as any at 20yds & under even against the heaviest of arrows but the 500grn bested all of them. I then shot at 25yd, 30yd & 35yd. At no time out of the countless shots did the 600grn or 700grn arrow out penetrate the 500grn arrow. The 400grn arrow was decent at 20 & under but fell off in the penetration department major after that! That one was out unless all you hunted was deer!

From zero to 35yds it was no contest as not only did the the 500grn arrow best the two heavier shafts but it beat them easily. I had the cement board layered so only the heads would stick through so no foam target came into play that the cement board was up against!

However at 40yds both the 600grn & 700grn arrows finally did catch up in the penetration department! No doubt momentum of the heavier arrows started to hold their own at the longer distance as was expected!

The 500grn arrow was the true winner here as most trad hunters do not shoot over 40yds that I know! This arrow was good for my draw wt. If ones draw wt differed to 50# then consider a 460grn to 490grn for optimum performance. If 60# then 550grn to 600grn.

At 55# a hunter would do well in the 490grn to 535grn, anywhere in there & you will be getting all the bow & arrows energies available! This is why the light arrow did not out penetrate, the arrow could not store the energy the limbs were providing! The same as too heavy, the limbs on a 55# bow only store so much energy, once used in a heavy arrow, penetration & trajectory suffers greatly at 35yd & under, not until longer distances come into play do they start coming to the fore!

I'm not saying that 600grn & 700grn arrows will not penetrate elk at under 40yds, but I am saying that the the 500ish arrow will do better than those at the shorter ranges of 40yds & under with a flatter trajectory!

[POk3s]

Elknut can explain this further as it was his test but I remember him talking about momentum. When you're using that heavy of an arrow your arrow can't reach high enough speeds....obviously. Those heavier arrows never reach enough momentum. Think about throwing a ball. you can throw a little rubber ball really hard but because it's so light it, it's not going to do much. You can't throw a 10 lb medicine ball very hard but it's heavy enough that it will still use that weight to hurt someone. Now pick up a softball. It's still relatively light but the extra weight compared to that of a softball AND the speed would cause more damage than both of them.

You need speed as well as weight to perform the best it can. Too light and you're not getting any penetration. Too heavy and you're not getting enough speed to get as much penetration as you could. I think elknut's numbers were somewhere between 420gr and 460gr or something like that for his particular setup.

[ElkNut1]

abschindler, Yes, I wrote that a few moons ago. (grin) Thanks for sharing that info. You are spot on in your thinking too, a 580grn arrow is a bit too much for a 43# trad bow if the hunter is looking for a balanced setup with both speed & penetration.

Pok3s, yes sir, some feel that you cannot ever go too heavy & that heavier will always out penetrate anything lighter, not true at all. First one has to define "heavy" it's only relative to the poundage a bow is being shot at & ones draw length. If hunters shot tuned arrows to their bows & arrows are in the 6.5--7grn per pound of draw wt they will receive about as much penetration as their bow is designed for. This is for compound bows at aprox 60# & up.

For Trad shooters ultimate penetration for Deer & Elk type species stay in the 9 grn - 11grn per pound of draw wt. Broadhead of use can come into play as well in choosing a good finished arrow wt.

ElkNut1

[G Posik]

For Trad shooters ultimate penetration for Deer & Elk type species stay in the 9 grn - 11grn per pound of draw wt. Broadhead of use can come into play as well in choosing a good finished arrow wt.

ElkNut1

This is true, but need to keep in mind the arrow needs to be tuned to the bow. just because you have the arrow weight the shaft spine needs to be correct. All of my bows (Recurve & Longbows) are in the 70-74# range. My arrows all range from 695 710 grains. I shoot wood and full metal jackets.

Glenn

[buglmin]

I got into this arguement in 2007 with OL Adcock and his thoughts on EFOC arrows. We spent three weekends shooting road killed deer and elk using me recurve and arrows that ranged in weight from 385 grains to heavy EFOC arrows that weighed over 650 grains. We used a Hooter Shooter shoting machine to avoid any human error and a laser to aid in aiming. We also tested various broadheads. All these arrows were tuned for my 57# bow. We used chronographs to measure arrow speed 15 yards in front of the bow and 25 yards downrange. It was a lot of fun, learned a lot of things, and my arrow/broadhead combos are based off these findings.

Broadhed shape and design plays a huge part in penetration, and the best broadhead we found was the Magnus Stinger. From lite bow/arrow set ups
to heavy bow/arrow set ups, the Stinger was the best flying, most accurate broadhead we tested.
I shoot lite carbon arrows from my 57# recurves and longbows, most in the 435 grain range. My FMJ's weigh in at 476 grains.
Think about it...an elks chest cavity, is roughly only 22" to 24" thick, on big, mature bulls. And ribs are actually easier to shot through then most guys think, cause they dont take the time to look and experiment with them, So, even 14" of penetration is going to give you enough penetration to get both lungs. I have no worries at all in what my bow/arrow combination will do, know I dont need heavy arrows or EFOC arrows to kill elk and mule deer. Shoot what you have confidence in, what makes you happy. Just shoot the sharpest broadhead you can get, and no matter what bow you use, compound or recurve, tune for perfect arrow flight.

[>>>---WW---->]

Here is what I think, take it or leave it. #1, I think Buglmin has it nailed down pretty good. #2, Just about everyone is getting way to technical. And #3, and most important of all, this is the ELK HUNTING portion of the forum. My thoughts, with no offence to anyone, would be to have this entire thread moved to the EQUIPMENT portion of the forum where it belongs.

So just to keep things where they belong and where originally intended, John: could you take care of that without upsetting every ones apple cart? I'd hate to see this wonderful forum turn into another Bowsite.

[sbschindler]

I guess the main question surrounding the intent of this thread is elknuts penetration tests and the results being you don't need a real heavy arrow to get the desired penetration, the physics of the test shows us that speed does play a big part in penetraton, its not the most important part of course but it at least has an equal part as does weight. so a good balance between weight and speed that tunes well is our goal..

[ElkNut1]

The reason for past testing in both Trad equipment & Compounds was to see real life results. There are so many newer elk hunters that really do not know what a good elk setup is regardless of their equipment. Threads like this came up where hunters would say just use whatever you want & you'll be fine, just make sure it's tuned to your bow. Others would come on & say go light weight arrows for speed & then you had the crowd that says you must go heavy for the best penetration. Well, this led to some testing starting a few years back to see what is what & how I could honestly & effectively respond to ones who were in the "need to know" group.

I'm not trying to sway anyone with their existing setups but facts are facts when it comes to the testing. I found out that every bow has a Peak Performance, you can go too light & you can go too heavy, simply put, be balanced & fall in the middle & you will enjoy both speed & penetration. This is why I stated up top that a compound shooting hunter would find his bows peak performance will fall into the 6.5 to 7grains per pound of draw wt. This means 70#X7 = 490grns at the upper end of the scale & 6.5X70# + 455grains at the lower end of the scale. This is not to say you cannot kill elk below or above these numbers, but I will say that your level of penetration will suffer when you get too light or too heavy when considering shots up to 60yds based on your poundage bow.

The same rule of thumb applies to longbows & recurves, the figures here are 9grains to 11 grains per pound of draw wt. for ultimate penetration. The more blades & larger the broadhead the heavier your arrow should be on the scale to achieve best penetration.

Regardless of equipment arrows must be tuned to that bow!

Ones would see this is not a debate, do the test yourself & you'll find these figures are right in there for ultimate penetration & speed combination.

What we cannot dictate in the woods is the perfect shot angles & scenario so it behooves us to equip our setups with best possible performing bow & arrow combo. Crap happens & animals can move or twist in an instant when we least expect it especially at close range, these moves will impede penetration regardless of your arrow wt. Be equipped for those worse case scenarios as well as the perfect broadside ones. Yes, ones can do something to aid their cause if they found themselves in this situation. Just because your setup killed an elk or even passed through doesn't mean it will happen on the next one. Here's an example where even one inch in penetration can make the difference.

I shoot a 56# longbow with a 500grn total wt. arrow, it had a 75grn brass insert & 125 grn head for 200grns of the 500 grns up-front. I killed a bull at 20yds with this setup, it actually passed through him. Now that's full penetration with a Snuffer SS 3 bladed head. The following year with the same longbow & arrow setup another bull came running in & stopped in front of me for a split second, I had a broadside shot at 14yds. I drew anchored & released in a split second, as I did he whirled towards me at the release of the arrow, the arrow struck him two inches to the right of his breastbone instead of the broadside shot I'd hoped for, yep a frontal shot on a mach 10 moving bull. I had not planned this shot, but I had planned for worst case scenario with my setup! That arrow went into the bull a mere 7"-8" yep not a lot of penetration but enough to carve him up well, he went aprox 200yds & was dead in seconds. With all the testing I'd done I know for a fact a much lighter or too heavy an arrow for that bow could have produced bad results. Even one inch could have been the difference in a lost animal there.

I've been in many situations where penetration in ones equipment can be the underlying factor. No one wants to be haunted with the thoughts of wounding an animal, do yourselves a favor & equip your gear for best results.

ElkNut1

[buglmin]

Paul, not trying to debate this, already have my answers and my results. But the guys that thing you need 600 or 700 grain arrows from a trad bow, and will argue this with anybody, needs to do their own experiment, using the right equipment. With a trad bow, the chance of guys short drawing happens all the time, causing different results and bad arrow flight.

A lot of guys shooting stick bows do have bad form, sloppy releases, or they torque the bow. They only way they can get decent arrow flight is by using heavy arrows with high FOC. Seen it way to many times...and I've heard this mant times, that is always the arrow/broadhead combo that resulted in low penetration. Not once have I ever heard the EFOC guys say it was a bad shot. Its always the equipments fault...If a 500 grain arrow is perfect for penetration from a 50# bow, why isnt it enough for a 55# bow? Can anybody show me why its not>

After our tests, we found that arrow weight wasnt as much a factor as the arrow/broadhead combination. Some heads were amazing in penetration, some a huge disappointment. Thats why I tell guys how important it is for them to try different combinations, and to always shoot the best arrow they can afford...you may not think it matters, but try shooting a big Zwickey Delta out of an arrow thats not perfectly spined and tuned...

HAPPY EASTER TO ALL...God Bless You and Yours...be safe, and be well on this very special day

[ElkNut1]

Anthony, thanks for your comments. A 500grn arrow is good for a 55# longbow but so is a 550grn one. (grin) They are in the 9grn to 11grn realm.

ElkNut1

[Swede]

I did some calculations on kenetic energy for different arrow weights and distances several years ago, by shooting through my chronograph.. I did not correlate my measurements to gr/lb draw weight, but had the information necessary to do so. I am wondering how Paul determined the ideal arrow weight range that was best for different types of bows and different draw weights?

[ElkNut1]

Swede, through 100's of arrows shot into a consistent substrate. It took weeks of shooting to see these results because of the many arrow designs I used. Many hunters sent me arrows over this period to test & see if there were any real world difference in their arrows when compared to others, there wasn't any earth shattering findings from one construction to another. However I found Gold Tips were not as strong as others, not a knock on them but they did have issues when shot into the material but also had their moments where they showed their toughness.

The testing material used was 14"X10" 5/16 thick cement board. The nice thing about the material was you could add layers to it to control penetration depths & it is not self healing so shaft diameters played little into true penetration. I layered them from 2 slabs to 7 slabs thick. Nothing went through 7 of them. Once I could get the layers determined I could see the true value from one arrow wt. to another. I also experimented with countless tip wts for comparisons & penetration depths. Lots of arrow wts were adjusted with wt type tubes within the shaft to equal arrow wts yet not mess with the spine which was tuned to the 65# bow used in the compounds.

After shooting enough arrows in the 350grn to 700grn wt range I could see them separate themselves in the penetrating dept. from 20yds to 50yds. After 100's of arrows shot repeatedly the results were easy to see. Nice thing about testing penetration with this cement board material is I could control passthroughs so foam or bag target material had no significant stopping power to influence true penetration. This cement board is very consistent in structure, there are no hard or soft spots like in bone, meat or flesh, too I shot multiple shots of arrow groups that were tested not just a single shot. I wanted the testing to be consistent & accurate.

Here's an example in this photo. The arrow that had the most penetration was 429grn, the 2nd arrow was 406 grains, look at the difference in penetration out of a 65# compound at 27-1/2" draw. The 406grn arrow is much faster but stopped quicker because it lacked the needed wt to maintain momentum. I shot these two arrows many times with the same results.

ElkNut1

[Swede]

Thanks for the answer Paul. I have read the results of several penetration tests over the years. Ultimately they get to be quite subjecctive. Your tests appear more quantifiable and defensible. Hundreds of shots make a difference. From what I am seeing in your picture it appears that even with all other factors being equal, (broadhead design and sharpness, arrow shaft material, stiffness and diameter, etc,) penetration is going to be more than just a function of kenetic energy.