Moultrie Products
Minimum Arrow Weight - K.E. Min's
Elk
Contributors to this thread:
NorCalVineyards 04-Jul-22
Jaquomo 04-Jul-22
wyobullshooter 04-Jul-22
creed 04-Jul-22
cnelk 04-Jul-22
Willieboat 04-Jul-22
HDE 04-Jul-22
JL 04-Jul-22
Corax_latrans 04-Jul-22
Beendare 04-Jul-22
creed 04-Jul-22
Treeline 04-Jul-22
Salt 04-Jul-22
Matt 04-Jul-22
[email protected] 04-Jul-22
JL 04-Jul-22
Knifeman 04-Jul-22
JL 04-Jul-22
groundhunter50 04-Jul-22
Jaquomo 04-Jul-22
joehunter 04-Jul-22
wildwilderness 05-Jul-22
Beendare 05-Jul-22
Ziek 05-Jul-22
JL 05-Jul-22
NorCalVineyards 06-Jul-22
JL 06-Jul-22
ahunter76 06-Jul-22
ohiohunter 06-Jul-22
Corax_latrans 06-Jul-22
NorCalVineyards 06-Jul-22
Corax_latrans 06-Jul-22
RD in WI 07-Jul-22
Blood 07-Jul-22
NorCalVineyards 10-Jul-22
Corax_latrans 10-Jul-22
04-Jul-22
My 14 yr old son has his first elk hunt up in Utah this Sept, L.E. as a non-resident. His current set up is a Hoyt Torrex at 58 LBS, 27" draw length shooting Gold Tip Kinetic Chaos arrows at 391 grains. We are going to go with a Viper Trick by Slick Trick on the end (391 includes the head). What are your guys thought's here. The Kinetic Chaos are 9.5 G.P.I. at 27" 400 spine. Is this plenty of K.E. to 45 yards of less in the rib cage?

From: Jaquomo
04-Jul-22
Yes, absolutely. KE won't be a problem. But you could add some weight up front to get the package over 400 gr. and it might help a bit with penetration. But no need to go overboard with FOC to get arrow weight up. You might want to add some weedeater string and bring the overall arrow weight up, and he may not notice any difference in trajectory out to that distance, with the added weight.

I like the 425-450 grain weight range for lower poundage bows, to balance between penetration and trajectory. Almost all of my partners and my elk have been killed with 52-57 lb longbows and recurves, with arrow packages between 410-450 gr.

Now let the real experts weigh in! (-: This thread should hit 50 posts shortly...

04-Jul-22
100% agree with Jaq. I also prefer a little more weight than 391. For comparison sake, I have a 26” DL and shoot 59lbs with a 436gr arrow.

From: creed
04-Jul-22
Good question and answer! I was wondering the same thing since I dropped poundage on my bow due to shoulder injuries. I am shooting 64lbs KE with a 425 grain arrow and was told that is marginal at best for elk. Think I am going to go with it.

From: cnelk
04-Jul-22
Do like Jaq said above - add some weed trimmer line. That should get you about 40 more grains of weight with not affecting the spine. Here's how I do it

From: Willieboat
04-Jul-22
You shouldn’t have a problem with that set up. Have had ladies do very we shooting 51 points and Easton 1916 aluminum arrows tipped with 4 blade Zwickeys.

Several were complete pass through. So I think what your doing will work just fine.

Good luck and can’t wait for the story!

From: HDE
04-Jul-22
Don't get wrapped up with K.E. It doesn't matter and is completely irrelevant to the equation.

His setup could use a little more weight though.

From: JL
04-Jul-22
Practice X100. IMO....nothing else matters if ya end up making a bad shot. BTDT and it sucks!

04-Jul-22
“ I am shooting 64lbs KE with a 425 grain arrow and was told that is marginal at best for elk.”

Ummm…. Do you have ANY CLUE how much more momentum/KE you get out of a mid-#60s compound r than the mid-#50s longbows & recurves that Lou is talking about??

It’s ridiculous. People make all manner of poor choices with their hunting set-up and shot selection, and then when they get poor penetration or lose an animal for reasons they will never be certain of, what do they do? “Man, I must need higher poundage!”

There are guys shooting #40 longbows whose arrows will zip clean through a #200 deer and keep on going, and there are guys who can’t get a exit on a #125 whitetail with compounds north of #60.

It’s not that the compounds are lacking in “energy”.

From: Beendare
04-Jul-22
A very efficient BH- like a 2 blade or a tapered 3 blade COC head- turns a low KE setup into a well penetrating arrow…..making KE less of a factor.

Take a page from the trad guys killing critters with 40# bows.

BH efficiency isnt as big a factor with a high energy compound but IME, those efficient heads make a big difference in low energy setups

.

From: creed
04-Jul-22

creed's embedded Photo
creed's embedded Photo
“ Do you have ANY CLUE how much more momentum/KE you get out of a mid-#60s compound r than the mid-#50s longbows & recurves that Lou is talking about??”

Yeah I have an idea. This is the last elk I killed with my setup. Went through both scapula. It’s just good to hear something from guys more knowledgeable and experienced than I am.

From: Treeline
04-Jul-22
Jaq is spot on. Have piled up a ton of elk with a 425 grain arrow tipped with a Snuffer. Off longbow from 57-62. A 40 pound compound will generate more energy than those bows!

I’d bump up the arrow weight just a tad with a heavier point and/or weight tubes/weed eater string. Have had issues with weed eater string popping nocks off in the past. I think it was because I just ran it straight without crimping like Brad show in his video.

I probably have a bunch of weight tubes if your interested I could send some your way. Let me know.

From: Salt
04-Jul-22
I have shot a bow for 35 years and never heard of the string trimmer line for weight. That’s a great way to add a little extra weight. Never too old to learn .Lol

From: Matt
04-Jul-22
If the 381 grs includes a 100 gr BH, I’d be inclined to bump that up to 125 grs and roll with that. In fact, that is almost exactly what I am shooting right now. You should be able to add that and still maintain more than adequately spine.

As stated above, a more efficient 2 or 3 blade BH may be a better choice as well.

04-Jul-22
The online Realtree calculator says my set up KE is ok for up-to pronghorn.

Deer, elk, caribou and bears would disagree. Upping arrow weight won't really change KE but it does change momentum. A great tune with a really sharp, well designed head trumps the numbers.

From: JL
04-Jul-22

JL's Link
Good discussion. It may be interesting to set your chrony up at 10, 20, 25, 30yds, etc and determine your arrow speed downrange and then calculate your KE at each distance.

This is an older article from Wasp. It has some good stuff in it towards the end.

How to calculate the Kinetic Energy of Your Arrow Aug 25, 2016

Kinetic energy is important for bowhunters to understand. It’s what helps drive broadheads deep and is a factor in an arrow’s penetration ability. Penetration is critical in bowhunting, and low-poundage bows should use the best arrow and broadhead combination for maximum kinetic energy. When an object is in motion, it has kinetic energy. When it strikes something, that energy is transferred. This is the basic force of impact – how hard an arrow hits a target. Kinetic energy, when related to bowhunting, is measured in foot pounds – the energy needed to exert a one pound force for a distance of one foot. Here’s the formula for calculating your bow‘s kinetic energy output:

Fps2 X Weight of Arrow / 450,240 = Arrow’s Kinetic Energy

Here’s an example of determining the kinetic energy of a bow shooting a 400 grain arrow with a 100 grain broadhead at 250 fps:

KE= 2502 x 500 / 450,240

Keep mathematical order of operations in mind and square fps first:

KE= 62,500 X 500 / 450,240

Next, perform all multiplications and divisions, working from left to right:

KE= 31,250,000 / 450,240

KE= 69.40 ft-lbs

FAQ’s about Kinetic Energy and Archery

Now that you know how to find the kinetic energy of your bow setup, you may how some more questions about how it relates to hunting situations. Here are some questions we get asked often:

I don’t have a chronograph. How can I calulate the FPS of my boat without one?

Read this blog: Calculate FPS of Your Arrows Without a Chronograph.

What’s the minimum amount of kinetic energy needed to kill a deer?

Many states set minimum draw weight requirements for bowhunters to adhere to. But draw weight alone is not an indication of penetration power. There are other variables to consider, such as what arrow and broadheads are used and the distance of the shot. Gold Tip, an arrow company, recommends a minimum of 25 ft-lbs of kinetic energy to ethically bowhunt deer. They also state 55 ft-lbs of kinetic energy would is sufficient for most popular North American game species.

My bow is set at the maximum draw weight, can I increase kinetic energy in any other way besides increasing draw weight.

Kintetic energy is effected by mass (an arrow’s weight) AND speed (draw weight). If you would like more kinetic energy, but are at the maximum amount of draw weight you can comfortably pull back, a heavier arrow will increase kinetic energy produced. But keep the laws of momentum in mind. A heavier arrow loses speed (fps) faster than a lighter one, so your bow’s sight will need to be adjusted and the maximum distance of shots will need to be considered. Use the combination of speed and weight that generates the highest kinetic energy from your bow.

I have found the combination of speed and weight that generates the highest kinetic energy from my bow, but am still worried about penetration issues. What can I do?

Choose your broadhead carefully. Usually, the larger the cutting diameter is on a broadhead, the more kinetic energy it needs to penetrate. The design and cutting diameter of a broadhead relates to sectional density. The Wasp Jak-Hammer, with a 1-3/4-inch cutting diameter, or the Wasp Z-Force, with a 1-5/8-inch cutting diameter, will perform best when shot from a bow producing at least 55 ft-lbs of kinetic energy. If you are on the lower end of the kinetic energy spectrum, use a broadhead with a moderate cutting diameter – something between 1-inch and 1-1/4. Wasp Archery offers many fixed blade and mechanical broadheads in this range of cutting diameter

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From: Knifeman
04-Jul-22
I add weight to my carbons with a simple brass insert, dont want to mess with line inside the shaft. I just never needed to, I know it works just fine. Yes it does change the spine to a point.

From: JL
04-Jul-22
^....another interesting thought. If one added that weedwhacker line to the inside of their arrow, that would distribute the added weight to the full length of the arrow. The question then becomes how much, if any, would that affect the spine?

04-Jul-22
Too much nonsense,,, more than enough, go have fun and kill something,,,, some of these guys will analyze stuff to death,,,,,,,,,,,, You got more power in a low poundage compound, then you have in high end stick bows

From: Jaquomo
04-Jul-22
I remember the first time I calculated KE with the little one-piece longbow my hunting partner built, after I killed my first P&Y bull with it. Whopping 41 lbs. Bull dropped in sight after busting through a rib and lodging in the offside shoulder. I looked up the expert advice and learned that my setup wasn't adequate to kill elk. Deer and pronghorns, maybe. But definitely not elk.

From: joehunter
04-Jul-22
If you are currently using the viper tricks in 100 grain - just move up to 125 and call it good. Go kill an elk.

05-Jul-22
As mentioned I would reconsider a 4 blade for either a streamlined 3 or 2 (maybe with bleeders) blade head if you want more penetration.

At that KE, Broadhead design, sharpness and tune will make more difference than another 25-50 gr of weight

From: Beendare
05-Jul-22
Trad gear was a big eye opener for me….as coming from a compound It was all about KE.

I don’t think the 47# recurve I killed a dozen critters with in the last 2 years makes 40KE but a two blade BH penetrates so much better than the other designs, that setup was a penetrating monster.

I blew 2 arrows through an 800# cow moose last year at 30 yds- Ive seen 70# compound guys with double the KE not do that with an inefficient BH.

Yeah more KE ….and more arrow weight is usually better and improves penetration….but those 2 blades are a game changer.

.

From: Ziek
05-Jul-22
He's in the ballpark. I would add a bit more upfront with a COC 3 blade BH like the VPA 125 unvented with a heavier insert, or even their 150 gr unvented head since he's up around 60#.

My wife is the second women to register a Colorado Big 9 with the CBA. Her set up has changed a bit as she gets older. She shot 50# when younger and has reduced to 45#, and lately a bit less than that with a Hoyt Carbon Element. At 45# and 24" draw length, she shoots a FMJ 500 with 125 VPA unvented 3 blade and a 20 gr. outsert. Total arrow weight is 421; FOC - 16.8; 199 fps. With well placed shots, she shot clean through elk, and a cow moose.

I wouldn't get hung up on KE, momentum, or especially speed. Shoot an arrow around 8 - 9 grains/# of draw weight, with good FOC, and a stiff shaft.

What no one seems to consider when talking about penetration is deflection at impact. Every impact on an animal imparts some deflection, and any deflection can have a significant effect on penetration. Reducing that is worth consideration. A 3 blade, COC, because of the design, resists deflection better than other designs, and leaves a better wound channel than 2 blades.

From: JL
05-Jul-22
This is likely old news for some of you old timers who live, eat and breath this stuff.

Now that I got a spiffy new chrony for ammo reloading, just for my educational purposes, I wanted to test the info in the Wasp link above. I used my trusty APA Black Mamba @ 70.5lb draw, a 427gr Gold Tip Pro camo arrow with a Rage 100gr practice head.

The closest one at ~4 yards was 295fps and a KE of 82.

The furthest at 21.5yds was 286fps and a KE of 77.

Sooooo.....I lost ~5 KE in 16 yards of distance. Doing the 9gr's per pound of draw weight....I could go up to a 630gr arrow. However the Wasp article suggests the laws of momentum may create a problem in FPS (and KE) loss with an arrow that heavy at longer distances.

Maybe at my next experiment, I'll increase the arrow weight and try to determine the FPS's at the longer distances. If we're using the 55 minimum KE from the article, from there one could get an idea of the max shooting distance with an arrow at "X" weight.

For you guys who excel at physics (not me), you might be able to take the above known distances, speed, KE and the estimated momentum loss and determine what the max distance would be (NLT a KE of 55) for the above bow and arrow set up?

IMO.....Capt'n Obvious may say it's probably not a bad idea to have a basic understand of your set-up's KE so you're not launching arrows at distances beyond your bow and arrow's KE capabilities. To be honest....I never gave the longer distances much thought until today's experiment with the chrony. Prior to the chrony, most of my close in hits were pass thru's. Probably won't change anything for me, so take it for what it's worth......

06-Jul-22
After a trip to the bow shop we are sitting at 421 grains and are trying out this KUDO 100 grain single bevel head. Current poundage is 55#. Our archery deer season starts this Saturday, so absolutely no more changes to the set up until after deer season ( Aug 1st)... Can't wait to see how these KUDO heads fly.

06-Jul-22
JL, do you have a Labradar brand Doppler radar

From: JL
06-Jul-22

JL's embedded Photo
JL's embedded Photo
Jay....no. It's this one. It does pretty good. I have the app on my laptop and cell. I can get the info after each shot on my phone. Pretty slick......

From: ahunter76
06-Jul-22
3 Elk shot at 35 yards. 1 with 53# Recurve 29" 2117 Aluminum shaft tipped with 125 gr 3 blade. 2 with 60# Compound, 29" 2216 Aluminum shaft tipped with 125 gr 3 blade. All Double lungs, complete pass thrus. You can do the math on arrow weight. Enjoy & good luck.

06-Jul-22
Thanks JL, I shot using someone else’s Labradar and captured the arrow speed from the bow to the target. But they are pricey

From: ohiohunter
06-Jul-22
How they fly??? I hope you know how they fly before sending them in the direction of an animal.

06-Jul-22
“However the Wasp article suggests the laws of momentum may create a problem in FPS (and KE) loss with an arrow that heavy at longer distances.”

The thing about Drag is that it increases exponentially with velocity. So a light, fast arrow maximizes Drag.

A heavier arrow will never be as fast as a lighter one starys out, so it’ll never encounter the same level of drag that a lighter one will. It WILL, however, always have more mass working for it to overcome the (lower) force of Drag against it.

Less drag ALWAYS. More inertia ALWAYS. Less velocity loss overall. More momentum upon impact.

The only downside is that the arrow doesn’t shoot as flat, even at distances at which the heavier arrow is traveling at higher FPS than the lighter one. The light one will always get there first and will always be more forgiving of elevation errors.

I always recall an article from probably 30 years ago in which the author asked Randy Ulmer what his maximum ethical hunting range was, and the answer was 35 yards. With sights and the rangefinders that were available at the time. I don’t recall if everyone had switched over to releases at that point or not, but we are still talking about a guy with amply demonstrated ability to shoot pretty well under pressure.

So I’m not going to endorse ANYBODY taking shots at elk over 40 yards - I don’t care who you are or how good you are on a target range - and I ABSOLUTELY would not endorse putting a 14 year old under that kind of pressure.

I’m pretty sure I recall seeing at least one poll thread here asking about average shot distances on Elk - there have likely been dozens- and it seems like it always comes out right around 30 or maybe a bit less. At least for the animals that were recovered.

06-Jul-22
45 yards was just a number plucked out of the sky, likely much less, hopefully sub 20, but surely not throwing arrows down range hoping and praying. He's been shooting out to 60 yards, that's the max his sight housing allows.... We will get as close as we possibly can to ensure best possible outcome for both parties, quick, clean, ethical kill.

06-Jul-22
Sounds good to me! There’s nothing like the rush of being close enough to hear the snot-bubbles pop.

I practice 65 yards every time I go to the range. Sometimes 80-ish. Cuz it’s PHUNN.

From: RD in WI
07-Jul-22
Good luck to your son on his elk hunt. I have never hunted elk, so I have no idea how durable they are or how well they stand up to arrows. I shoot a micro-diameter arrow and use a heavy insert to get the weight I consider heavy enough for big game hunting. I suggest A LOT of practice, so the shooting part of the encounter is automatic and your son can concentrate on the hunting part - when to draw, that sort of thing. Once again, best of luck.

From: Blood
07-Jul-22
I’m shooting a 555gr at 289 fps. I’ll take a heavier arrow at a fast speed over a lighter arrow at a faster speed all day. The heavier arrow stays faster at distance than a lighter arrow, loses momentum slower and penetrates better. Shoot straight everyone :)

10-Jul-22
421 grains 60lbs Kudu points hit 8inches low, bummer. Viper Tricks hit true like field points out of his bow.

10-Jul-22
“I’m shooting a 555gr at 289 fps.”

I don’t know whether to think “HOLY $#!+!” or just call bullschitt. According to Stu, that’s over 100 FPE.

To equal that at my 27”-ish DL, I’d need to be drawing about #120. You think they’re still making Game-Getters in 2419?

So now I just need to find a bowyer who will warrantee a bow at 4.4 GPP.

Maybe I’ll just stick with my #62. It’ll probably squeak out about #45 FPE, maybe #46.

And I guess I should just go ahead and burn my #55 @ 28”recurves for firewood. They‘re not worth even 40 FPE and the #[email protected] R/D LB probably won’t crack 34, so that’s obviously just a target bow.

Thank God we have BowSite where we can get straightened out on these things!

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