If I have a group of bows that are the same dimensions but are different poundages and shooting the same 650 grain arrow will a heavier pound bow be that more powerful?
Is it worth it to shoot a 65lb bow because of it's more efficient than the 60 or 55lb bow?
I'm thinking of getting a new bow that will work for elk and moose and was told a that bows over 60lbs
aren't going to produce enough improvement to justify shooting a bow over 60lbs.
Any latest tech info proving or disproving this theory?
Get the one that you can shoot the best under pressure. At hunting distances any of the three will put that arrow through the boiler room. With practice and learning the trajectory of the arrow the one you are more comfortable with should be your choice.
Kinetic energy is derived from two factors, mass of projectile and speed of the projectile. A lot of the newer designed bows will cast an arrow faster than the older designs. A new r&d type bow at 50# may well cast faster than an older design at 55 or even 60 #. If you are buying a new bow anyway why tug 60# when 50 does a better job.
As long as you don't have a very short draw length, it think it has been shown that you would be fine with 55,60 or 65#. As said above, whichever you shoot the best under hunting conditions and have the most confidence in. That being said, all thing being equal, you can achieve flatter trajectories with a more powerful bow, which can be useful. You will hear alot of people pointing to diminishing returns with increasing draw weights, but nobody can step up to the plate to quantify that or help you determine if it is worthwhile to shoot heavier or not. The gain from going to 65# from 60# is not much less, if at all, than that of going from 55# to 60#. Pretty much just people justifying their choices to stick to lighter weights.
I understand that there are some physics involved, where a bow or limb design supposedly reaches its max efficiency, and the mass weight required in the limbs for a heavier draw brings diminishing returns on the ability of those limbs to transfer energy to the arrow. Like an Olympic sprinter who muscles up their legs so much that now they are very strong, but too heavy and slow.
I think Fred Bear calculated that phenomena to occur typically around 65#. That may be different these days, with traditional bow limb design becoming so advanced.
But as you can see in my signature, I shoot a slightly heavier bow than that, and with a longer draw, as well. Maybe the heavier weight really isn't necessary... but I just like feel of the heavier bow. I shoot my 68# limbs almost exclusively these days.
Thanks very one, far as shooting I can shoot a heavier draw very accurately too. And I like my arrow getting there quick for a stickbow.
Flintim you make a good comment about the newer modern design and material of bows vs. older bows.
I'd like to know if a modern 70lb bow is that much better at delivering the arrow than a modern 60lb bow vs. 50lb bow? Or is the dimenishing returns just not worth it after a certain poundage? Anyone have the research to back it? Anyone willing to do the research to give a qualified answer?
And for the sake of argument, I think everyone gets the picture a well placed arrow from any bow gets the job done....
If you test in an apples to apples controlled test. Bows of the same design will produce about the same in a 9gpp @ 28" test. The problem your setting out is shooting the same arrow in bows over a 20 pound range.
The arrow is not going to be spined correctly for a 70 and a 50 pound bow.
I find that once you go past 60 pounds in our designs you start loosing performance due to limb mass.
For elk sized animals shoot the bow you have the most confidence in and can shoot the best. All will deliver a proper arrow and broadhead and do the job.
Mike
Here is what I see about heavy vs light poundage. If you shoot a lighter bow with a fairly heavy arrow for hunting, say 10-12gpp, it will work fine and kill many a critters. If you shoot a heavier bow with a fairly heavy arrow, the same 10-2gpp, you will probably get around the same speed, but because your arrow weight is much heavier, you will have much greater momentum such could help on marginal shots or on bigger, tougher critters.
I am an advocate of the idea that a guy should hunt with as much draw weight as he can shoot well under pressure situations! For me, that is 50# at my 29" DL. If you are just target shooting, go as light as you want, and have fun.
JMHO!
I am also pretty confident that if you have a well tuned 650 grain arrow, and you can shoot the bow well, you could kill just about anything you wanted to (at least in North America) with any of the bow weights you asked about in your original post.
Bisch
This is what I kind of thought but times have changed over the past 30 years. Thanks guys!
Time to start shopping for a new longbow from Liberty bows and Blacktail.
What Bisch says....shoot (especially true on bigger animals, ie - elk) the heaviest bow you can shoot accurately - all other things being equal. There is a lot of difference in designs and how they handle arrows, but in general, that rule of thumb is gospel as far as I am concerned. Of course, WHEN this matters is going to be when things are not perfect - the animal moves at the shot, you only have a quartering away shot - you hit a bone - etc. That is when the extra poundage is worth the effort. And it happens to all of us. That being said, two holes in a critter (entrance and exit) is as good as it gets no matter the poundage.
Also, don't discount your arrow setup...just as important IMO as the bow. Great flight that stabilizes quickly with a super efficient broadhead that penetrates deep or clear through.
If the bow is well designed you'll have the most power with the 65#, then the 60#, then the 50#.
Which one you use is up to you, but they'll all work. Which one do you shoot the most accurately cold?
It doesn't surprise me that there is less of a performance increase from bows as draw weight increases. Isn't that the way it usually is with life in general? For example, the amount of effort you put into something generally produces greater results when you are first learning to do something than after you have almost mastered it. This is called the "learning curve." We're willing to put in the extra effort to get a small result because we want to be the best we can. Similarly with a 65# bow: it's going to shoot better than an otherwise equivalent 60# bow, maybe just not as much better than a 60# bow shoots compared with a 55# bow. Howard Hill shot a 90# bow. I assume he knew it probably didn't shoot much better than an 85# bow, but since he was able to handle it, that's what he wanted to shoot.
Reminds me of the old story when a news reporter asked a Texas Ranger why he carried a .45? The Texas Ranger replied that he carried a .45 because they didn't make a .46.
I think Bisch hit the nail on the head.
Don't know much about diminishing returns and all the technical aspect of bow design and all that stuff. I would be fascinating to see some data on the subject.
Blanket statements like that really do not make any sense.
Bow efficiency depends on bow design.
If we take an English longbow design I know for a fact that it will not reach even close to maximum efficiency at 65#.
A short glass recurve will hit that point quicker but a short wooden recurve will hit max efficiency at a higher draw weight.
A longer glass recurve will hit max efficiency at a later point and a longer wooden recurve at a later point as well.
There's also different style longbow and recurves with all kinds of different designs so again, a blanket statement like that makes no sense.
But regardless of that, a higher draw weight will always throw a heavier arrow faster which gives you a better trajectory, a more stable arrow, and more hitting power.
Not to mention a heavier draw weight gives other benefits as well such as a cleaner release and forces you to use the proper muscles to draw the bow leading to better form more often than not.
The bow limbs will also be more stable and less prone to torque and being thrown off course due to a poor release or grip.
All things have points of demenishing returns. The few bowyers that I have talked to say very similar things as Mike. The low 60 lb range is the point where their bows efficiency numbers start to decrease as they increased poundage. This is very difficult to test and prove.
The amount that efficient decreases is negligible in my experience, and mostly used as an excuse. If someone doesn't want to shoot a heavier weight because they don't feel it is necessary or because they don't shoot that as well, those are much better reasons. The rest is smoke and mirrors. Even if the gain going from 60 to 65# was only 90% of the gain going from 55 to 60#, that you a substantial gain, and I doubt the dropoff to a even that steep.
QuoteOriginally posted by pdk25:
The amount that efficient decreases is negligible in my experience, and mostly used as an excuse. If someone doesn't want to shoot a heavier weight because they don't feel it is necessary or because they don't shoot that as well, those are much better reasons. The rest is smoke and mirrors. Even if the gain going from 60 to 65# was only 90% of the gain going from 55 to 60#, that you a substantial gain, and I doubt the dropoff to a even that steep.
The main problem with talking about bow efficiency is that we have no clue what the bow design is, the length of the bow, and the material(s) it's made out of.
If we take a long, longbow it will reach maximum effeincy at a higher draw weight than say, a short 58" recurve.
I agree with you though that the max efficiency thing is mostly a moot point.
A case in point is that there's no way that a 60# bow will cast a 700 grain arrow as fast as a 70# bow even if maximum effeincy is reached at 60# and both bows are the exact same design.
IMHO the advantage to heavier weight in draw is to shoot a heavier arrow at close to the same velocity that a lighter bow will shoot a lighter arrow! I have a 75 lb recurve that kicks out 600 grain arrow at 212 FPS. It spits my 800 grain arrows (which you have seen in person) at about 180 FPS. Now my 65 lb longbow is much more pleasant to shoot, and sends an 834 grain arrow at about 165 FPS. I am good with that set up out to around 40 yards. With a lighter arrow I can stretch that to 50.
For me the main advantage in using high poundage bows is that they like and are more efficient with heavy arrows and they do so at an acceptable speed. The impact of a heavy arrow at 12gpp is noticeable and it makes for sure a difference in penetration on critical situation, plus the bow is more quiet.
I shoot a 550 grain arrow out of my 50# bow and I wouldn't hesitate to hunt elk or moose with it. I do t worry about the science aspect of it. Sharp broadheads and a tuned bow wil get the job done....
One would think that grains per pound would be a good predictor of arrow velocity, but I have found this not to be true when comparing bows of different draw weights. I like to tune my bows and arrows using arrows of about 9 gpp. It seems the higher I go in bow weight, the lower velocity a 9 gpp arrow produces. That is, typically a 40# target bow might produce 190 fps using a 9 gpp arrow, whereas a 50# hunting bow might produce 180 fps with a 9 gpp arrow (both of the bows recurves of comparable quality). Is this just another reflection of the subject being discussed in these posts, that increases in bow weight produces diminishing returns in efficiency?
Yes, but I think yours is an extreme example, and not likely to be seen across the board using bows of the same design. That would be amazing to reach that level of diminished returns at such a low draw weight.
Actually, the example I gave, while not based on any kind of a scientific study, is representative of more than a few bows in the 40# - 50# range. Since I typically shoot targets with bows in the 40# range, and typically hunt with bows in the 50# range, and chrony all of my bows, I have come to expect that speeds obtained with 9 gpp arrows are going to be less with heavier bows than with lighter bows. Maybe the figure I tossed out of a 10 fps difference is not correct, as I haven't done an actual mathematical analysis, but the concept is accurate, as it relates to the bows I have chronied. Perhaps the reason is less because of diminishing efficiency as bow weight increases and more because of the physics involved in the force required to get a certain mass to a certain velocity (or perhaps a combination of the two)?
I'm not real sure if this is what you guys are talking about or not,but I think it is. Pretty neat little video anyway.
https://www.youtube.com/watch?v=eJ4qPNaPxTU
Dave, I am saying that for the same exact style bow with nothing altered, including string type and silencers, other than the poundage of the limbs, I have never seen a drop like you are describing, even at highter draw weights.
Alexander, the YouTube video you linked to is on point. Shooting various bow weights at 10 gpp, the arrow velocities recorded were essentially the same. The arrow velocity was actually a little higher on the heavier bow, although the difference was probably statistically insignificant. Obviously, my measurements were different, and I'll have to ponder why that might be.
In my own experience, I find that very heavy bows have a lower per pound/spine requirement. While a lighter bow of the same design can shoot a higher per pound/spine ratio. There is always some gain as weights go up, but as Byron Fergusson stated, there is a point of diminishing returns. I think that point varies with different designs.
Even if the heavier bow is 10fps slower it will still shoot flatter at longer distances because as an example, a 650 grain arrows sheds speed at a much slower rate than a 350 grain arrow would.
I'm of the opinion that arrow speed within 25 yards is mostly irrelevant though.
I personally can shoot both a 600 grain arrow and 450 grain arrow and there's practically no change in my POI within 25 yards and even at 30 yards the difference is negligible.
For me personally, around 35 to 40 yards is when arrow drop starts to factor in and I can tell the difference between different weight arrows.
But by that point I'd prefer the heavier arrow even if it's 10fps or so slower because it will be more stable in flight (wont be effected by wind nearly as much) and will shed very little velocity down range.
QuoteOriginally posted by forestdweller:
I personally can shoot both a 600 grain arrow and 450 grain arrow and there's practically no change in my POI within 25 yards and even at 30 yards the difference is negligible.
My experience has been different. My gaps are about twice as big going from a 655 grain arrow to a 550 grain arrow. But maybe that's because my lighter arrows are shorter (amplifies the gap).
The way I see it . . .
If you have three bows: 65#, 55# and 45#. Say you kill a deer with each. Then 45# is the most efficient of the three. ;-)
McDave, have you tried comparing speed on your heavier bows with a heavier arrow as well? Just curious if they were slower than the 9 gpp arrow, like I would expect.
QuoteOriginally posted by Longtoke:
McDave, have you tried comparing speed on your heavier bows with a heavier arrow as well?
Of course, when I compare arrow velocity at 9 gpp, I am shooting a heavier arrow out of the heavier bow. But I get your point. If I compared arrow velocity at 10 gpp or 12 gpp, it is possible that I might get a different result.
Dynamic efficiency is strictly a function of the efficiency of your bow at a known grains-per-pound of draw weight at a specific draw length. Dynamic efficiency isn't a standard number. Different bow designs have different efficiencies. But if you have a brand "X" bow at 65# and the same brand "X" bow at 45# it will shoot the same GRAINS PER POUND ARROW at the same speed if all other things are equal. Same bow length, same string length and weight, same brace height, etc.
After watching the video that was posted, and hearing from others, I think my conclusions from my own testing were flawed. I don't have two models of the same bow to test with, so I'm really mixing apples and oranges when I test a 50# brand A bow against a 40# brand B bow using 9 gpp arrows in both cases. While all my bows are high quality, I may have a personal bias in selecting higher performance bows for my lower poundage target bows, and higher reliability bows for my higher poundage hunting bows.
But learning new things is a primary reason I participate in TradGang, and I think I just learned another one.
Great discussion going on here!
One point I'd like to add.
Draw length plays a significant part on how an arrow performs.
A person shooting a 50lb bow at 28" draw compared to a person shooting a 50lb bow at 29.5" draw will for all practical purposes of this discussion will perform differently.
What do the experts think?
Just remember....a,diminishing return is STILL a return.
Yes, even though, at least for me, the spine per pound was less with the bows that were over 80 pounds, the increased arrow weight has a major effect on the penetration, or in my case the yards of pass through. The last deer I shot with my 96 pound bow, up hill to a field edge with a dowel stuffed into the front half of a Microflite 12. That arrow skipped and bounced a long way after going through the deer. Of course, a deer is in no way a 400 pound boar. I had that set up for moose hunting, then when I had the chance to take a very easy shot, I couldn't do it. Turns out I have a soft spot for moose.