100% of the time. Not saying it will kill the deer everytime, but your odds of getting a fatal hit will go up 10 fold
Your statement is false, there is no way you will increase your odds ten fold young man. KE is the key to penetration and you can actually lose KE by going heavier and slowing down the speed of your arrow. Here is a good read, enjoy! http://bowsite.com/bowsite/features/practical_bowhunter/penetration/index.cfm
The following link might help with a decision. I would hit your local pro shop and see how fast you are shooting the 393gr arrows and see how fast a 367gr setup shoots. You can use the calculator in the following link to get an idea of the approximate KE you are shooting. You will likely be within 1-2# of KE by switching and will still have plenty to take Whitetail's. http://bowsite.com/bowsite/features/practical_bowhunter/penetration/index.cfm
Absolutely, however, I see that this argument is gaining neither you or I anything and is probably only going to result in confusing the OP. I'll agree to disgree. You have your beliefs of the situation, I have mine.
This is an excerpt from a scientific study: http://tradgang.com/ashby/Momentum%20Kinetic%20Energy%20and%20Arrow%20Penetration.htm Given two arrows of equal momentum, but with one deriving a greater portion of its momentum from mass than the other, the heavier arrow will change velocity (decelerate) at a slower rate as it passes through the tissues. In other words, the heavier arrow will retain a higher percentage of its impact velocity at any given time period during its passage through the animal’s tissues, thus it also retains a higher momentum at any given point during the time required for the arrow to penetrate. Another way of saying this would be that, though the heavier arrow is traveling slower, it takes a longer time to stop. The result is that the heavier arrow will have a greater impulse of force than does the light arrow. It is momentum that gives an object in motion the tendency to STAY in motion. The greater the contribution of the object’s mass is to the resultant momentum the harder it will be to stop the forward progression of a moving object. Anyone who has pushed a car in neutral and then tried to stop it will understand this. The more of a moving object’s momentum that is derived from its mass, the more TIME it takes to stop it with any given resistance force. It is common for proponents of light and fast arrows to counter that the faster arrow will have traveled a greater distance through the tissues in the same time period than will the heavier, and slower, arrow. This would be valid were it not for the nature of resistance forces. As the arrow’s velocity is increased the resistance does not increase equivalently. The resistance increases exponentially. The resistance of a medium to penetration is reliant on the square of the object’s velocity (assuming objects of a given coefficient of drag; i.e., using arrows with the same external profile, material and finish). In other words, if the arrow’s impact velocity doubles, the resistance increases by a factor of four. If the impact velocity quadruples, the resistance to penetration increases 16 times! The effect of exponentially increasing resistance is easy to experience. Try holding a hand out the window of the car, while the car is going at a velocity of 30 miles per hour (which is only 44 feet per second), and feel the air’s resistance against your hand. The resistance is very slight. Now accelerate to 60 miles per hour (a mere 88 feet per second). The velocity has only gone up by a factor of two, but the air’s resistance to your hand passing through it is now four times greater. Now imagine the effect on an arrow passing through tissues. Tissues are more solid than air. They have a greater density. Their resistance to an object’s passage is higher. Visualize the effect as an arrow’s velocity increases from 150 feet per second (a fairly typical velocity from a mid-draw weight traditional bow) to 300 feet per second (as from a top line compound bow). Let us now assume an arrow weighing 700 grains for the slower bow (150 fps is easily achievable with that weight arrow and a ‘traditional’ bow) and a 390 grain arrow for the faster bow (the advertised velocity rating for one of the newest compound bows on the market, using that weight arrow). The slower arrow has 0.466 slug feet per second of disposable net force. The faster arrow has 0.519 slug feet per second. Lets also assume these two arrows are of same materials, have equal physical external dimensions (easily achievable), and both have perfect flight characteristics. The tissue’s resistance increase is totally dependant upon the velocity of the arrow. The lighter arrow has 10.22 percent more disposable net force (and 123.2 percent more kinetic energy) than the heavier arrow but, because of its higher velocity, it is met by four times the resistance to penetration. Which arrow will penetrate further in real tissues? Empirical evidence from the outcome studies provides an overwhelmingly definitive answer. Both the frequency and degree to which the heavier, slower, arrow out-penetrates the lighter one is of such a magnitude that it must be viewed as the norm. The bold red is my doing but it sums things up rather nicely
I don't see as to why I had to provide any such documentation? it's a general rule of thumb. I just had a hamburger for dinner, do you need a video of it for proof? However, brucelanthier filled in with the documentation you wanted. Thanks bruce
Bruce's data fails to provide absolute proof that a heavier arrow will increase a kill shot 10 fold as you stated. I argued the fact that KE is the key factor and loosing 1or 2# would still allow the poster to kill deer. a 600 gr. arrow out of a Trad bow shooting 170fps will have a KE of 39# a 403 gr. arrow out of my Hoyt shooting 309fps will have a KE of 85# I don't have a PHD but I like my chances a hell of a lot better than the Trad guy. Other points to ponder. You might have better penetration in theory by scientific data as Bruce's study pointed out, but the heavier arrow will have more surface area to slow the arrow down. You also need to account for shaft diameter vs. broadhead insert diameter. If the shaft thickens at the point of contact from the broadhead to the shaft you will have increased friction. At the end of the day I provided a link and an option for the poster to play with numbers to see if his combo would kill deer. Everyone in this thread has preached heavy arrows and the fact is that two arrows of equal KE might have a difference of 10-15% penetration based on momentum, that hardly backs up your claim of increasing a kill shot ten fold.
I stated my point early on and it got shot down but that's ok. I see now there ARE others that do see it a bit differently.....same as I..... THANKS! Just watched a DVD and the founder of PSE, Pete Shepley, said he would take KE over weight anyday. He should know his stuff.
Look, like I said earlier, i'm not going to argue any more. This is going no where. It's turned into a battle of opinion and i'm done. You have your facts and I have mine. later
It is a little ironic that the industry norm is KE and not momentum Until the myth of killing percentage increases at tenfold can be confirmed I am calling B.S. on backcountry, he knows his statement is greatly exaggerated.
The industry is trying to sell you speed and a faster bow every year so what do you think they are going to promote? Dr. Ashby isn't trying to sell anything but facts. Personally, I find nothing wrong with using speed/KE as a measuring tool but I do think it is good to have more of an overall understanding about the whole process of what happens in different scenarios (arrow weight/speed, BH type and so on) when shooting animals with them. What I posted by Dr. Ashby is just a very tiny part of his overall research. I highly recommend reading through as much of it as you can. http://tradgang.com/ashby/
Yeah.....If I was selling compounds, I'd push that "science", too. To the OP......just remember, unless you go to extremes, HEAVIER IS BETTER. Yes, there will come a point of diminishing returns. But, unless your IQ is lower than a fern's, I'm bettting you'll never get there. Good luck. And, btw......when Bruce says something.....write it down.
U heavy is not always better. The poster wants to drop arrow weight and wants to confirm he will be able to get the job done. He has plenty of KE to get the job done and can get a flatter trajectory which will open more shot opportunity. Why lob an arrow when you can shoot flatter and still kill your game? There is no reason he can't go lighter. At 367gr he will be shooting 6.67gr per lb of pull weight and will have enough KE to take an Elk according Easton's chart.
Tell me, at known yardages, the advantage of "flatter trajectory". So.....at 280fps, you're "lobbing" arrows? And, at 300fps, you're not? Listen, you can prejudice any criteria to fit your agenda. Just remember, there are 3 types of lies....."Lies; Damn lies and statistics". Keep the numbers "reasonable", and I'll stand by my assertion....."Heavier is better".
Dear clueless in North Carolina. The poster is already shooting 252fps with the heavy arrow. Why are you referencing 270 and 300? Flatter trajectory allows for a smaller shooting window. Granted you graduated yourself to Trad God in the last two years and consider yourself a deer knowledge god but you fail to answer the original question and keep spinning like a Kenmore washing machine. Not everyone wants to be Robbinhood like you Jeff, they just want to know their setup will kill deer and the answer is yes.
