Mine was 420 grains with a 100 grain Exodus QAD with bow at 67#!
Did you like your setup or are you changing total arrow weight?
ElkNut1
Definitely love my current setup. My only complaint is how far the arrow travels after it goes through the animal! ;)
Next year it will be 560gr with a buzzcut from my Recurve
Andy
Wish it was heavier but I dealt with it
Last 10 deer or so shot right thru.
Last 2 elk one 53 yds hit right behind shoulder on right shattering left humerus. Not a pass thru.. Pretty sure if I didn't hit humerus it would of been a pass thru.. 125 recover down steep hill, both lungs..
#2 quartering to @ 34 yds hit left scapula in soft part, arrow stopped half way in right tenderloin. Hit left lung and liver. 80 yds recover.
Ed
Looks like lots of folks shoot arrow weights in the 480 grain plus range! My Son & I too for many years shot arrows in the 475 grain to 565 grain range out of 70# compounds & we took lots of elk with these setups but rarely had a pass-through? It was like about 15% of the time we would have one? Most arrows stayed in the elk, it killed them but I still would wonder why not many would pass all the way through?
This led to a months worth of testing various weights & penetration value. After all said & done we found that for 65# to 70# draw weights that arrows in the 415 to 440 grain weights kicked butt in the penetration category out 45yds which is what most our elk hunting distances were within! This led us to stay in that weight range & see if we experienced a difference in pass-throughs on elk.
We've taken 10 bulls in the last 4 years, our arrows have weighed in at an average of 420 grains & all with 100 grain heads, up to that time we only used 125 grain heads or heavier. Well the results have been very good! Out of the last 10 elk with the new setup we have had a pass-through on 9 of the 10 elk, only reason it wasn't 10 out of 10 was one was a frontal shot, on him the arrow completely disappeared into the elks chest & was buried aprox 3"-4" passed the nock. That was aprox 30" of penetration since we both shoot 27" arrows.
With those results to date we won't be changing things up! I enjoy trying different broadheads as long as they are 3 blade or better!
Thanks for all the comments so far!
ElkNut1
Be careful not to equate your results with lighter arrow weight instead of increased hunting experience, other component choices, or just happenstance. Everything else being equal, 500 grns + will out penetrate lighter arrows consistently.
Not necessarily.
We found that arrows in the 420 to 440 grain category out of 65#-70# compound bows did much better at distances from zero to 45 yards in the penetration department than arrows in the 500 grain or heavier category.
The results transferred into a positive with all the pass-throughs we've benefited from since going to the 420 grain+ total arrow weights. Our arrows are much flatter shooting too leaving a bit of room for error on those misjudged yardages, within reason of course. Thanks!
ElkNut1
Yes, I agree, but at some point there is a diminishing return. I did a little backyard experiment one weekend and placed a chrono in front of a target and stepped back in 10 yard increments out to 40 and got speed readings at the target from each distance. What I saw is the heavier arrow's speed falls off at a faster rate than the lighter arrow (the slope of the velocity curve was steeper). Granted, the arrows were 400 and 435 grains. I did not use anything in the 500 grain range, but would like to see the comparison.
Also, the numbers for momentum and KE were pretty much the same between the two arrows: one lighter and "faster" the other heavier and "slower". So, someone can use an arrow in the 400 to 435 grain range and expect the same outcome - from my bow anyway.
Really? Better repeat your testing.
The point is, there is a range where weight doesn't matter as much as one might think. There are many, many other factors that can and will influence how far an arrow might penetrate, and that doesn't mean hitting solid leg bone vs one rib. The broadhead sticking out the other side is really all that matters - I'd call that a complete pass through. I'd call that mission accomplished. The arrow laying on the ground on the opposite side is irrelevant. This may open a nasty can of worms, but oh well.
I'll wager that a 500 gr arrow shot from my bow won't necessarily out perform the 400 gr arrow set up the way it is from that same bow. Haven't tried it yet, but that is what I'll speculate. All I can do is spout off about what I know and I have had the same result from one year to the next on animals of comparable size, one arrow at 400 grains and one arrow at 440 grains - both with complete pass throughs (arrow laying on the ground, opposite side). I don't know much, but I know that.
I did experiment with loading the front ends up to 200 grains on one arrow, it did very well even though it's total weight was only 390 grains. Most arrows were your basic aluminum inserts with 125 grain field tips.
In 65#-70# compounds the superior penetrating arrows were the 420 grain to 440 grain total weights. The heaviest arrow I used was 519 grains, it lagged so far behind at 45 yards & under that I saw no reason to up the weight any further.
Now, after the 45 yard mark the heavier arrows in the 475 grain to 519 grain arrows started to catch up as they held their energy better for longer ranges. If a hunter wants to take 60 yard to 100 yard shots then yes this is where the heavier arrows will shine! But again you can still go Too Heavy or Too Light, there is a balance depending on draw weight mostly!
It's not complicated at all, after all the shots it was easy to see what arrow weights were best for us since we do not shoot at elk passed 50 yards. Of course I wouldn't hesitate to put a 2nd arrow in an elk at 70 yards either, there's still plenty of energy to sink an arrow at that distance!
Happy Holidays everyone!
ElkNut1
I would submit, if an arrow has to have a higher point of aim to begin with (angle at which it is shot), or "nose dive" sooner assuming a zero deg inclination at the shot, then you will have a different resultant opposite force acting along the length of the shaft (both x and y components relative to the angle) at which it is shot or "nose dives".
It is negligible at most normal bowhunting and shot distances, but it is there. Maybe my results are flawed, but I doubt it since several shots were done to get a consistent average in each scenario. The only data points recorded were from arrows with POI 1 foot above the chronograph. Flawed data would be to incorporate a speed rating of 254 fps when the other shots come in at and avg of 273. The trendline is the trendline. In a controlled lab, perhaps the outcome would show different. But in real world scenarios when many other factors come into play, you get what you get.
Maybe the results are just ambiguous and don't really mean anything. What it tells me though is that I can use any of my arrows from the lightest (HEXX) to the heaviest (Axis) I have and get pretty much the same result. In spot and stalk country, I'll choose the lighter of the two. It also tells me I have options on arrows in case I'm on an out of town hunt and realize I ran off and left my arrows at home for some dumb reason and the only thing I can find at the local shop is a dozen Easton Flatlines.
Once again - the point is: arrow weight is important, but it doesn't matter to the magnitude one might think when bouncing around +/- 40 grains. Otherwise, people who shoot light poundage and light arrows accordingly would not be able to take down a 368" bull at 31 yards.
I think someone earlier on mentioned a happy medium of 430 grains or so to give what would likely be the optimum best for a hunting arrow on elk size animals - speed and potential to get the arrow to stick out the other side.
There will be a point of diminishing returns, economics will support that.
Was the arrow tip allowed to exit the media or was the media thick enough that the arrow tip was always contained?
"Yes, the coefficient of drag across the vanes and along the length axis is the same. "
Frontal drag is greater for the faster arrow.
"So, why does a heavier arrow "nose dive" or hit the ground sooner (distance) than the lighter arrow, back to all things being equal?"
It won't.
If both arrows were shot perfectly horizontal from the same elevation above the ground, the heavier arrow would hit closer to the shooter, but not "sooner" as you proposed. Both the heavy and light arrow would require the same amount of time to hit the ground since they are falling vertically at the same rate.
The air in contact with the arrow doesn't know one is heavier over the other. The coefficient for drag, friction, or whatever is a constant. The plane at which the axis of length for the arrow in contact with the air will have an adverse effect on the arrow's performance. Think of the concept of air brakes for an airplane.
Going back to what I originally said for the purpose of this discussion, in real life hunting scenarios, a change in arrow weight won't necessarily give more advantage. There is an optimum between weight and speed that gives the "sweet spot" for trajectory and penetration. So far, I've only seen one attempt to show this, whether the data is skewed or not. If the only thing I've done is to cause someone else to do this who is a better shot than me to get "better" data to tell the whole story then I've succeeded.
Happy hunting.
I'm now using an Elite E35 @82#, shooting a 525 grain Gold tip kinetic 200 - Wac em 125's 3blade. They are creating right around 100ft lbs of ke. I've had no problems with pass thru's other than finding my arrow on the other side.
No, it isn't. the coefficient of drag is dependent on several factors, one of which is the speed of the object relative to the fluid, thus the faster of two identical size arrows, regardless of weight, has a higher Cd.
"There is an optimum between weight and speed that gives the "sweet spot" for trajectory and penetration."
There is a trade off between trajectory (speed) and penetration that is highly personal, NOT an optimum "sweet spot".
Let's get it on!
This testing helped me to appreciate when an arrow was too light & when & arrow was too heavy for the draw weight being used. It showed us the "balanced weight" that did the best.(ballpark weight)It helped us to achieve great penetration & speed at the same time, best of both worlds! (grin)It was very simple to see after 100's of shots of many different brands of arrows at 340 & 350 spine mostly, I did use one 400 spine fmj as it tuned perfectly with the 65# bow with 27" arrow length.
We then carried those tests into actual hunting elk & were amazed at the pass through's when in the past with 500ish grain arrows would consistently stay in the elk. It has worked well for us & I'd recommend it to others.
Here's a photo of a 40 yard shot into the cement board, top axis arrow is 429 grains, 2nd & 3rd arrows are fmj at 469 & 472 grains, one fmj is 400 spine & the other is a 340 spine, just tried it for grins to see if it would make a difference because of spine, it did not. I took multiple shots with these & all tested arrows & distances & results were the same. Notice in the photo the fmj's did not penetrate all the sheets & the axis arrow did! It was like that in a 1/2 dozen tries. Thanks!
ElkNut1
ElkNut1
The cement board did very well, it helped shed light on the better arrow weights to use during our elk hunts! As mentioned above we were getting a pass-through 2 out of 8-10 elk with heavier setups! After the testing we are nearly 100% with our revised setups! That is a real world result & exactly what we were hoping for! Thanks again!
ElkNut1
525gr for longbow (53#)
No tests, no formulas. Just seem to be the most accurate for me at my hunting distances.
Be careful arguing with Purdue. One of my daughters is a Boilermaker grad and they don't lose many technical discussions :-)
I am making a switch and going to try Gold Tip in 2016
I will either be shooting around a 500g Kinetic or 440g Pierce
125g Slicktricks
It didn't shed any light on anything. It's highly probable that there WAS a very small difference in penetration, even with your very minor weight difference of 40 grains. (Hint: There should have been some minor difference even between subsequent shots with the same arrow). Even if it was only a millimeter or less, that's a difference. Anyone care to guess how such a small difference, when shooting a field point through cement board backed by foam, translates to shooting a BH into animal tissue? Another hint. Guessing invalidates the results.
All you did was set up an idiotic test to validate your foregone conclusion. By the way, I've been bow hunting for 32 years. What I've observed is that the heavier the arrow that was used, from just over 7 grains per pound of draw weight to just under 10 grains per pound of draw weight, in bows from 45# to 75#, the better the overall penetration. So my observation cancels yours. ;-)
The coefficient of friction for both arrows will be the same if their size and shape are the same. However, the actual drag is not only a function of the coefficient of friction, but also velocity (among other things). In fact, a doubling of the velocity will quadruple the drag. Again, the faster arrow will have more drag and slow faster.
"If the lighter arrow's rate of velocity decay is faster, then all light arrow's should hit the ground sooner in all aspects relative to it's heavier counterpart."
You haven't thought this through, if I understand you right. Just because an arrow is slowing faster than another does not necessarily mean that it going slower than the other. A flu-flu arrow shot from a 70# bow will slow quite rapidly. However, at say 15 yards it could still be going significantly faster than a standard arrow shot from a 15# kid's bow, despite the flu-flu decelerating at a faster rate.
ElkNut1, thanks for the info.
Ziek, thanks. I've been bowhunting for 45 years. Through trial & error I even get things right sometimes! (grin) Have a great day!
ElkNut1
That's the problem with "real world result"(s). There are too many variables to confidently assign one variable to the observed results. Two experienced hunters can reach different conclusions based on their personal anecdotal evidence.
I remain unconvinced that a 420 gr. arrow will out penetrate a 520 gr. arrow out of the same 70# bow despite the results of shooting through concrete. ;-)
Kelly
Gentlemen, the reason you tend to use a constant number as a coefficient is because the velocity is changing over time, that's no secret. There is nothing to keep the object in this case propelling forward like the engines of a jet or car. To do textbook homework problems like I did some 20 years ago (and have since forgotten some of the finite results, requirements, and methodologies) you need to use a changing velocity over time at each distance giving A Lot of numbers to work with. In short, you start to use calculus and integration to describe what you are saying. Your true coefficient is a result of the integration at time zero (v = distance 0) and time final (v = distance at impact). This would be the velocity number used in your calculation to find the Reynolds number you would need to eventually calculate your coefficient.
Your coefficient will either come from a resource book or through testing in a wind tunnel.
In my example above - the coefficient you claim to be a "magical number" is a difference in velocities for the arrows of less than 10 fps at the most. Boys, that is hardly anything to get excited about and it just really ain't gonna matter that much.
The above data shows that in pretty much most all real world hunting situations, you will not see a noticable difference in a hunting arrow within 40 grains of each other at most real life hunting shot distances with a bow.
Comparing arrows 100 grains apart is not a reasonable comparison. If you go by the same logic that a faster arrow will slow down by the square of it's velocity (and by the way, KE does the same thing) then eventually, the slower arrow will in fact be going faster and be the "bad guy", then the lighter arrow will catch up in theory - all things being equal. This can't and won't happen because your arrow will hit the ground first in all cases.
You can theorize all you want, but you cannot and should not think that pure theory is at play and nothing else is. Because your arrow may also hit a pocket of air that has a slight difference in density and throw off your coefficient calculation. To say that only one variable matters is nonsensical at best.
Guys - stick to a published constant and your life will be much simpler, other wise brush up on the calculus because that's where it needs to go.
One thing you keep looking past is that 9 of the 10 elk taken were pass-throughs due to the results learned, before that not even close to that. I was just sharing our findings not trying to change your mind or anyone elses.
Please take a 600 grain arrow & a 440 grain arrow, tune them & shoot them out of your 70# bow at 40 yards down to 10 yards. You can shoot them through layered plywood, new foam target, 3D target, cement board or the like, you will find as we did that the the best penetrator will be the 440 grain arrow at that drawing weight & distances. No not science but with any & all those tests being done (I did them all) why would all of a sudden when shot in a game animal would the 600 grain arrow now miraculously out perform the 440 grain? This is not a debate, just trying to use sound logic.
If you choose a lower poundage or higher poundage bow then the better total arrow weight would change with it. To date we've taken elk (not dangerous game) with 382 grains to 565 grains all in the 65# to 70# range compound bows, they performed best with the 420 to 440 grain arrows. When choosing to shoot our longbow & recurve we use 9-10 grain per pound of draw weight arrows out of our 55# - 60# trad gear. This is a better combo for us when arrow speeds are only 175 fps to 190 fps. I mention these couple of things so you wouldn't assume that we use 420+ grain arrows out of just any bow or poundage, thank you sir!
ElkNut1
HDE, I wasn't using a constant for Cd. It always changes relative to velocity, and other factors. But you are correct in that a representative Cd or Reynolds number, is often used, especially when the range of velocities are fairly limited and for comparison purposes between similar objects when operating in similar environments at similar speeds, like cars, etc.
"Comparing arrows 100 grains apart is not a reasonable comparison."
Sure it is! Or perhaps I should ask why not? Actually comparing arrows 200 grains apart is reasonable since some shoot arrows out of 70# bows at the recommended minimum of 350 grains, and some shoot heavier than 550 grains.
I've been saying that for years.
"This can't and won't happen because your arrow will hit the ground first in all cases."
That is exactly what happens. If you shoot 2 arrows of significantly different velocity off a cliff, where there is time for the physics to play out, they both reach the same terminal velocity. At extreme hunting range a light and heavy arrow can reach the same speed too. Obviously this is dependent upon the initial speeds and arrow weights.
"To say that only one variable matters is nonsensical at best."
Who said only one variable matters? The laws of physics are not theories, that's why they call them laws. We can misapply them, misinterpret the results or fail to account for all the factors, but that does not nullify the established laws of physics.
Both your test and ElkNut1’s appear, at first glance, to defy commonly held beliefs and laws governing penetration and velocity. However, there are no bad tests. Every test gives the only results that it could. I can assure you that all of the laws of physics were followed. Our job is to figure out why our test results did or didn't meet our expectations, what other laws of physics are at play and to be sure we do not extrapolate test results to places where they do not apply. Perhaps the same phenomenon (for now) that occurred with the cement boards also occurs in elk. Who's to say it's impossible?
ElkNut1, my own tests for penetration in foam have been non-conclusive. Some arrow brands showed virtually no difference in penetration at different weights, yet another brand showed about 10% more penetration for the heavier arrow. There does seem to be a corilation between arrow diameter and penetration in my foam tests. I need to do more tests.
I didn't go elk hunting this year, but in the past used arrows from 395 - 450 grains. No plans for any major changes. I shoot at about 55# and have a 27" draw length (41 ft-lbs KE). Trajectory is my main concern. Penetration has not been an issue, so I shoot just enough weight to keep the noise down.
My mediocre testing showed the best of both worlds, speed & penetration, it serves us well when a quick yardage estimation is needed, being off 5 yards or more with a faster arrow yet not sacrificing penetration can be the difference in a kill or a wounded animal.
Ziek/Purdue, maybe we can look at it this way sir. If you were to take your 70# bow at 28" draw & put it in a drawing/shooting machine. ( yes they make them) Now take 7 arrows in 20 grain increments from 380 grain to 500 grains. Now shoot these arrows from the machine into a controlled substance & shoot them all at 30 yards, you will find one of these weights will out perform the rest in penetration value.
For instance, lets say the best penetrating arrow is the 440 grain arrow, this would mean that the three under it do not reach the top pyramid peak as they lacked the depth of penetration compared to the 440 grain arrow. If you continue to go lighter in weight the penetration lessens even more.
Now take the next arrow that is heavier than the 440 grain arrow, 460 grains, it too will lack the penetration ever so slightly, if you continue to go heavier & heavier to 500 grains 700 grains to a 1000 grain arrow your penetration does not increase it will get to the point that the arrow will not even stick into the target. So there is an arrow weight for that draw weight that will perform best with all things equal. As some mention 15-20 grains either way of the peak weight is not a big deal, this allows a ball park number where we can still shoot a penetrating monster arrow that compliments our draw weight setup.
Personally I want the combination of penetration & speed! Yes, 500+ grain arrows will kill elk but why sacrifice penetration & speed when there's a better choice?
Not trying to sway ones arrow choice, just pointing out why we made the switch ourselves. Use what you're confident in!
Ziek, the difference between trad gear setups & compound setups is arrow speed. A 55# longbow cannot cast a 440 grain arrow as fast as today's 55# compounds or any arrow weight for that matter. Thanks!
ElkNut1
Agreed.
"For instance, lets say the best penetrating arrow is the 440 grain arrow."
Lets just say it is the 500 gr arrow, because that's what it will be.
..."your penetration does not increase it will get to the point that the arrow will not even stick into the target..."
Agreed again, BUT that point is somewhere way above 10grns/# of draw weight.
"Ziek, the difference between trad gear setups & compound setups is arrow speed."
OK, Now explain why it doesn't work for a 100# compound, and why 440 grains is somehow the magic weight irrespective of anything else.
I agree that there is a "balance" between trajectory (speed) and penetration. But that balance is a personal decision based on a persons tolerance for trajectory and perception of how important even a little additional penetration may be. Even one more inch after expending most of it's energy passing through bone, heavy muscle or worse, a stomach full of grass, can make a difference. I can control whether or not I take a shot (trajectory tolerance) and I rarely shoot past 40 yards (another reason light arrows are popular - bowhunters trying to extend range beyond reason). No matter how good a shot I am, or how deliberate and disciplined I am on shot decisions, I can NEVER control where or what the arrow actually hits once it leaves the bow. So I choose a heavier arrow, among other things that effect penetration and are in themselves, tradeoffs.
I don't care what weight arrow anyone else shoots. What irritates me is when they try to rewrite the laws of physics to validate their choice.
Please shoot what you're comfortable with & we'll do the same! Good luck to you on all your future hunts!
ElkNut1
With compound bows, there's energy to spare which overcomes the inefficiencies of a setup and the end result is still a dead elk, which is the reason most shrug off the physics. Not so with longbows and recurves, or when shooting larger game if you want to have the best chance for success.
If you've studied Ashby's work (and most haven't, though they'll say they have), you'd notice that arrow weight is actually sixth on the list of penetration enhancing factors.
Another problem I see is folks testing in foam. Penetration into foam is a function of the arrow speed, arrow diameter, and friction coeff. of the arrow shaft. Weight is not much of a factor if any at all (other than it can't be zero) and the resistant force of foam is basically linear as a function of the arrow speed for a given arrow. Don't believe me? Then why does my pellet gun with a 7 gr pellet and 8.0 ft-lb of energy blow completely thru my foam target while my 70 ft-lb arrow only penetrates 12"?
In soft tissue (like an elk), the resistive force is much different and is similar to air (at least when bones aren't encountered), where the resistance increases as a square of the velocity. This means that increasing the KE thru speed gives penetration gains, but the incremental gain becomes less and less as the speed increases. This is well documented in Ashby's work (which actually uses real animals as the test medium), as well as in countless bullet terminal ballistics studies done by both the US Military and LE, as well as lots and lots of aerodynamics testing. Another well known and studied concept is sectional density with regards to projectiles and penetration/drag (look that one up if you are interested).
Here's another example of test medium (pretty non scientific). I shot my 670 gr broadheaded arrow out of my compound with 70 ft-lb of energy into my bag target (the kind that is basically filled with rags and that cottony polyester stuff). The bag stopped the arrow before the BH could punch out the back. I then shot my 530 gr BH arrow out of my longbow with only 35 ft-lb of KE. It blew completely thru the bag target (fletching and all) and went 12" into a foam target several feet behind. Both BH's were cut on contact (though different makes) and I repeated the test with the same result several times. Study of Ashby's work explains the differences in penetration well, but it also illustrates that test medium makes a huge difference when talking about penetration on game animals.
In the end, shoot whatever you want and what you are comfortable with. If you are a compound shooter and don't care about the physics, that's fine, you've got enough KE to overshadow any of your system's shortcomings and can probably go thru your entire bowhunting life not caring. But, if you pick up a longbow or want to hunt really big game or want to maximize setup efficiency, then do some research first.
It's funny, because this all stuff has already been studied over and over at the scientific level, but all the science gets killed in a single instant by some guy shooting 5 arrows in his backyard. Don't get me wrong, the backyard tests are fun, but the interpretation of the results, the resistance by many to certain proven facts, and the lack of understanding of the many many simultaneous factors at work leads to conclusions that are flat out wrong in many instances.
Good shooting and best of luck to everyone,
I was with you right up until you said your long bow at 35lb KE put a 530 grain arrow through your bag target yet a your 70lb compound bow wont put a heavier 670 grain arrow through it. Are you saying that if the 670 grain BH arrow had been shot out of your long bow it would have had the same results as the 530 grain arrow? That might make more sense to me. Were the arrows compatible in FOC? Or is your 70lb bow perhaps old? Sorry, im not trying to question you, Im trying to wrap my head around it.
In Economics, a condition exists where adding additional capital (equipment) or labor to increase output costs more. These are known as the marginal product of capital and labor (aka diminishing returns). Though it probably does not exist, there is a marginal product of speed and weight. Backyard testing is the only way to figure that out because theory and laws will only show you what should happen and is merely a starting point because of the limited resources most have. Science can't always capture the unexplained (by what resources are available and used), that is why safety factors and "fudge" factors are used, or compounds that are able to make up the difference.
No body shoots a bow the same way, therefore no bow is tuned the same way, but all are close. This variance is what will give different results and cause people to make different choices. That variance is the fudge factor.
The 550 gr arrow had a higher FOC (27% vs 19%), higher mechanical advantage on the BH (grizzly vs a muzzy phantom), and a different sharpened tip configuration. All of which are discussed by Ashby as being significant performance factors. I would actually attribute most of the difference to the BH more than anything else, though FOC probably helped (both are fairly high though, much higher than what most shoot). Also, to clarify, it was 35 ft-lb vs 70 ft-lb, kinetic energy, not draw weight.
The big thing for me though was the eye opener of having exactly the opposite of what you might expect happen, and not by a little bit, by a lot. But also, that it matches experiences in the field on actual game animals. Traditional shooters have been blowing arrows thru elk for a long time. The compound came along, and it seems less people get pass throughs (or the same amount at best), even though there should be more due to the added KE from the newer technology. The end result may still be a lethal hit, so many folks just keep trudging along.
Goes back to my statement earlier that lots of kinetic energy masks other inefficiencies in a setup, but leads to the false conclusion that more KE is the best way to increase penetration. (BTW, increasing arrow weight increases KE slightly out of the bow, but also downrange more significantly). Increasing KE is one way of increasing terminal performance, but as Ashby has demonstrated, its not the most efficient way, and all that KE is easily squandered by ignoring other factors that are more important and often overlooked for various reasons (i.e. why worry when you are killing elk anyway?).
Best of luck,
That makes a little more sense to me. Im thinking the end result out of the compound with the 550 grain arrow set up would have been the same if not better than it was shot out of the long bow. Yes, Im sure the broad head choice was a huge factor. Thanks for the clarification.
Physics laws apply to archery. 100% of them, 100% of the time.
Ballistics charts show 22-250 w/50 grain bullet at 1620 ft lbs. Great flat shooting round for varmints out to 300+ yards. 45/70 with 405 grain bullet is 1590 ft lbs energy and is used extensively as close range backup for griz/brown bears and has filled more railroad cars with bison than can be imagined. And the trajectory of a rainbow.
Roughly equal in energy. Opposing ends of real world performance. Far more extreme differences than the archery topic at hand here, but the example shows the physics.
The only real compromise from the same bow (within performance design specs)is lighter arrows give better trajectory.... but less momentum, which is the lions share of penetration potential.
Conversely more weight gives higher momentum, but decreased trajectory. Take your pick. Those are the facts. Physics. Increase one, decrease the other, to some degree or another.
I shoot right around 460 for everything. Not bad trajectory, hits fairly hard as well. For me, that's my compromise.
An engineer will use both the "laws of physics" and the laws of economics when designing a bow, an arrow, a broadhead, etc.
Hate to break it to you, but, when someone asks what benefit you get when using a heavy arrow or a certain brand, you just used economics. Physics just tells you why something happens, not why you choose to use it.
Oh yes, economics is used in archery to, 100% of the time.
".... rather not do that..." looks like you made a choice based on a possible outcome.
I will say that the difference of wind effect on heavy arrows is noticeable. Shooting out of the garage into the wind at 60 yrds, minimal drift vs the lighter arrow.
I agree with above. Tune it well, get comfortable with what you shoot, and stay inside your ability. Hit them in the right spot and most will work.
http://www.youtube.com/watch?v=t4RGcyZ_gJY&feature=youtube_gdata_player
http://www.youtube.com/watch?v=VAfK0sBsZBw&feature=youtube_gdata_player
Maybe you can help out here why this is so? Thanks!
Here's a perfect example in the photo, it's a 30 yard shot into several sheets of the hardi backer cement board, I repeated these shots several times & everytime the outcome was the same? Top arrow is a 390 grain Victory arrow with 200 grains up front, middle arrow 429 grains axis arrow & bottom arrow 519 grains fmj arrow. All shot out of a 65# compound.
ElkNut1
Ziek, great questions to be considered for sure. The axis arrow & fmj arrows both were exact length & both with the same design field tips. Shot after shot produced the same results.
I'm not a mathematician & do not pretend to be but I have common sense. (grin) I can see of those two which one was kicking butt over & over! The cement board is very consistent & can imitate solid bone contact, if the 519 grain arrow was the better penetrator it should have done better, it didn't. Even at 20 yards it lagged way behind as it did at 30 yards.
If you were a new hunter & you stood by my side as I shot those two arrows above numerous times & you did not have a clue as to either of their weights which one would you want in your quiver on your elk hunt? Thanks!
ElkNut1
Dudeist. You left out a major one that everyone experiences on almost every shot into an animal. Deflection caused by the impact of the arrow with the animal. Just so much as nick a rib with one blade on entry (or worse a glancing bone hit with a trocar type tip) and you will get some amount of deflection. Once it starts, there is nothing to stop it from continuing (the fletching at that point is just along for the ride). Often it's not enough to make a big difference, but there are choices you can make to reduce it, like BH design and increasing FOC. None of these equipment choices I mention make a lot of difference by themselves, but they start to add up.
I like how the arrows I am currently using with higher FOC are performing. Shot through an elk this year at 27 yards and have no idea where that arrow went.
Are the diameters of all three arrows exactly the same? What about the finish of the shafts?
Just trying to help explain your results. A 10% change in arrow weight shouldn't result in a 25%-30%change in penetration in any direction no matter how you swing it which leads me to believe shaft friction, or maybe arrow flight/ tuning to explain the results.
If it's really hard to pull the arrows out thru that cement board, then shaft friction would be the most logical explanation.
The cement board has not gripping or friction value like foam would. The 430 grain arrow just flat out penetrates the others! (grin) Thanks!
ElkNut1
This past season I had a complete pass through on a large 7X7 elk using a 505 grain FMJ, with a 125 grain Helix broad head and a 75 grain insert, resulting in a 17 % FOC....shot with a 60lb compound
You have got to be kidding.
You could never get a consensus on how the tests should be ran.
No one would believe the results unless the results conformed with their preconceived ideas.
Sorry, I couldn't resist.
ElkNut1
I find this to be my favorite combination of speed, penetration, and quiet. Don't forget that heavy arrows are much quieter.
I've shot a number of smaller whitetails where the arrow passed through. After the arrow goes through the brush and leaves on the other side the deer were startled from the sound. Several times this had made them come closer to me because they never heard my bow.
Paul, thanks for the info!!!!!!!!????????????????
ElkNut1
Yes, the 55/75 is a .400 spine arrow, tune it well & you should be good to go! Hit them where they live! (grin) Good Luck!
ElkNut1
ElkNut1
ElkNut1
