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...
Several were complete pass through. So I think what your doing will work just fine.
Good luck and can’t wait for the story!
His setup could use a little more weight though.
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”.
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
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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.
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.
As stated above, a more efficient 2 or 3 blade BH may be a better choice as well.
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.
JL's Link
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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At that KE, Broadhead design, sharpness and tune will make more difference than another 25-50 gr of weight
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.
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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.
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......
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.
I practice 65 yards every time I go to the range. Sometimes 80-ish. Cuz it’s PHUNN.
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 #50@28 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!
