Point of diminishing return ?? Where ya think?

[Sapcut]

Many trad guys think there is a diminishing return at some point regarding arrow weight. Where do you think that “point” is at each end of the spectrum?

Have you ever seen arrow penetration on bone hits compromised due to the arrow being too light but fast? Have you ever seen arrow penetration compromised on bone hits due to arrows being too heavy but slow?

I built an arrow today in hopes to find out if I can reach the heavy end of the point of diminishing return. Although it will either be on a pig or a deer this fall.

The new “Spearrow” is 1361 grains and 30% FOC shot from my 71# Widow recurve. It is a GT Ultralight 300 inside a 2213 shaft, 100 gr. insert, 150 gr. behind insert, 200 gr. adapter and 313 gr. TuffHead broadhead.

It flys good and confident with trajectory and accuracy to about 20 yards. Most of my shots avg. 10-12 yards. Looking forward to blowing things up!

 

[Montana Slim]

Well... looks like you're all set!

 

[Sapcut]

Well duhh. Spearrows are why dinosaurs are extinct.

 

[Rob5589]

I just started with a single string so I have no idea. Interestingly enough, and completely 180 degrees from your arrow, I was recently listening to a podcast with Randy Cooling and his arrow set up was around 480 grains out of a 55lb recurve. Says he uses it for everything, including an upcoming polar bear hunt in the next couple of weeks.

 

[oldgoat]

I really think the diminishing return will be in the form of accuracy when arrow gets too slow and that all depends on the bow and how efficient it is

 

[FLS]

I think you will see diminishing returns on the extreme ends of the spectrum. Limited penetration on the light end, an arrow that drops like a stone on the heavy end. I don’t think your penetration will be hindered on the heavy end due to the weight you shoot.

 

[Sapcut]

I really think the diminishing return will be in the form of accuracy when arrow gets too slow and that all depends on the bow and how efficient it is

I think you will see diminishing returns on the extreme ends of the spectrum. Limited penetration on the light end, an arrow that drops like a stone on the heavy end. I don’t think your penetration will be hindered on the heavy end due to the weight you shoot.

Yes. on the heavy end......the very unacceptable trajectory may come into play as the limiting factor before the actual mass weight of the arrow. But to determine that "point" you must need the same bow and draw weight creating a constant in the equation along with constant arrow weight.

 

[Btaylor]

I am doing this from memory so I may be off on the numbers a little but seems like 16 gpp was where momentum peaked. With a 71# bow that would be 1136 grains. Your setup is a touch over 19 gpp. Only way to know how it will work is go shoot some stuff with it. If the arrow flight is is good and accuracy doesnt suffer, it should kill 'em dead.

 

[ledflight]

@Btaylor good point. If one can measure the velocity then you can measure momentum and see where that starts to decline.
From my experience I have seen huge drops in shot noise when going up 100 grains when playing around with different arrows.

 

[thinhorn_AK]

Those are awesome, I've been trying to learn more about this so I can build myself some dangerous game (black bear arrows) but its hard to figure out where to start. I guess I could just order the 950g grizzly sticks.

 

[Sapcut]

I am doing this from memory so I may be off on the numbers a little but seems like 16 gpp was where momentum peaked. With a 71# bow that would be 1136 grains. Your setup is a touch over 19 gpp. Only way to know how it will work is go shoot some stuff with it. If the arrow flight is is good and accuracy doesnt suffer, it should kill 'em dead.

Arrow weights and speed I shot today and some I had documented from the past with same bow. The momentum continues to increase as arrow weight increases, at least to the heaviest arrow I have so far.

812 gr. 169 fps .608
852 gr. 163 fps .616
875 gr. 160 fps .621
1077 gr. 150 fps .716
1120 gr. 147 fps .730
1361 gr. 138 fps .833

 

[Btaylor]

Arrow weights and speed I shot today and some I had documented from the past with same bow. The momentum continues to increase as arrow weight increases, at least to the heaviest arrow I have so far.

812 gr. 169 fps .608
852 gr. 163 fps .616
875 gr. 160 fps .621
1077 gr. 150 fps .716
1120 gr. 147 fps .730
1361 gr. 138 fps .833

I dont know. You cant expect a guy to rememborize everything. It may have been the KE that peaked around 16gpp. Seems like that was in some of the Original Ashby stuff that I read back early to mid '90's.

 

[Sapcut]

I dont know. You cant expect a guy to rememborize everything. It may have been the KE that peaked around 16gpp. Seems like that was in some of the Original Ashby stuff that I read back early to mid '90's.

Yea. No problemo. Very well could be KE. It is not a factor in penetration anyway. When I have a chance to put the heavy spearrow in an animal I will have a better idea, and only just an idea, if the momentum at this level still equates to blowing bones up like all the lighter arrows on the list do. I am sure they do.

 

[Btaylor]

The quoted material below is what I was remembering. It seems relevant to the discussion though. While momentum may continue to increase does that correlate to increased terminal performance? Logically, to me at least, it seems like we would all be best served by pushing up towards the point of highest efficiency that we can and still maintain the arrow flight and accuracy that best fits our hunting scenarios. I honestly have no idea if there are terminal performance gains to be seen when pushing TAW well beyond the bow efficiency threshold.

"1) Maximize the bow’s efficiency. That means shooting the heaviest arrow one can while still maintaining a trajectory that is adequate for ethical bowhunting ranges.

Most bows show a rapid increase in efficiency with increasing arrow mass up to the point of approximately 12 to 14 grains of arrow mass per pound of bow draw weight. (The exact point where the rate of efficiency increase begins to decline varies from bow to bow and shooting style to shooting style. There are many variables, and the value of a chronograph to the shooter should not be underestimated.) Beyond this point of arrow mass per pound of bow draw weight a bow’s efficiency will still increase as the arrow gets heavier, but the rate of efficiency increase slows down."

 

[Sapcut]

The “bow efficiency” concept is very vague subjective. However, my favorite arrow flight trajectory is right in the range quoted. For me, 900 grains has a slight but noticeable arcing trajectory. It allows my eyes to imprint that flight on my brain, I guess. Not too flat, which I do not want. I have learned if my arrows are flat shooting to 18 yards then it is too light.

 

[sndmn11]

I'd say that arrow weight stops increasing at the point the shooter isn't proficient at 40 yards. My guess is that is 600gr +/- 50gr for most people's ability.

 

[Sapcut]

I'd say that arrow weight stops increasing at the point the shooter isn't proficient at 40 yards. My guess is that is 600gr +/- 50gr for most people's ability.

Why 40 ? That is probably more than twice the avg. trad bow kill distance.

 

[bbassi]

I dont have an educated opinion about your original question because I've never put that much thought into it, but I'll bet those arrows make that Widow dead quiet!

 

[sndmn11]

Why 40 ? That is probably more than twice the avg. trad bow kill distance.

From my 14ish years with a recurve and all the folks I know who shoot one, that seems like the cut off point for who is genuinely good, and those who you hope the animal about runs them over.

I also think practice should regularly happen past the hunting effective range.

Lastly, I think that is a distance where form causes things to open up greatly. Akin to a 70 yard compound shot, or 500 yard rifle shot. If a person has good form with their trad bow the drop from 30 -> 40 yards isn't too much for the brain to compensate for "instinctively". If one is going heavy enough that their brain can't calculate the trajectory, I think that is a diminishing return.

 

[Sapcut]

From my 14ish years with a recurve and all the folks I know who shoot one, that seems like the cut off point for who is genuinely good, and those who you hope the animal about runs them over.

I also think practice should regularly happen past the hunting effective range.

Lastly, I think that is a distance where form causes things to open up greatly. Akin to a 70 yard compound shot, or 500 yard rifle shot. If a person has good form with their trad bow the drop from 30 -> 40 yards isn't too much for the brain to compensate for "instinctively". If one is going heavy enough that their brain can't calculate the trajectory, I think that is a diminishing return.

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