Too heavy? Arrow building

[MattB]

Read this in article for perspective. which would be easier to stop? A 16penny nail at 400fps or a railroad spike at 250fps.

The one that weights 27x more and has ~9.5x more KE would be harder to stop, but that has nothing to do with anything in so far as this conversation is concerned because the numbers are poorly scaled.

Comparing a tennis ball at 250 fps versus a raquet ball at 300 fps would be a much more relevant comparision (4% KE difference, which is about what I saw in my arrow tests).

 

[MattB]

That seems to be where I have found the sweet spot for energy with ke. It will vary depending on the setup, but it has held true for a lot of bows around 70# and 28-29 inches. You start getting too heavy and you loose ke.

Momentum will keep increasing with weight, but your ke will start to fall off with the reduction of speed.

Interesting, I've run that sort if test a few times with bows in the range you cited (27.5" and 29" DL, 70#), an KE kept going up until i ran out of heavier arrows to test (north of 9 gr./# both times)

 

[Billy Goat]

Interesting, I've run that sort if test a few times with bows in the range you cited (27.5" and 29" DL, 70#), an KE kept going up until i ran out of heavier arrows to test (north of 9 gr./# both times)

Too of my head I can't remember what the total weight was. I know I had arrows up over 800 grains and bows 72-74#.

Probably some of the bows are more efficient with heavier versus lighter arrows. It was several years ago I did the testing.

 

[Bmoore]

Not to diverge too much from the OP's post/thread, but I "run" a similar setup (73#, 29.5", 286fps and 492 gr) for elk. When some people find out I shoot the same arrows for whitetail, they say that it's overkill. Not sure I understand the opinion, as it's not like using a 300 WM when a 243 would do (thereby possibly destroying more meat), as I can't "over penetrate" when my goal is to always have a complete pass-through on any type of animal.

My setup isn’t exactly common in the whitetail woods. Many people look concerned and say it’s overkill, but like you’ve said, I can’t over penetrate the animal. My thought is if it can kill an elk or moose, why would I downgrade for whitetail. Will it kill them too good?

 

[jmez]

Guy on AT did that test a few years ago and arrows were well beyond anything you would ever shoot before they started losing KE. It was well over 1000 grains.

 

[Greenmachine_1]

That seems to be where I have found the sweet spot for energy with ke. It will vary depending on the setup, but it has held true for a lot of bows around 70# and 28-29 inches. You start getting too heavy and you loose ke.

Momentum will keep increasing with weight, but your ke will start to fall off with the reduction of speed.

I would love to see your raw data for when this happened, because I'm not sure KE could actually fall off. I suspect if someone were to start losing energy on their heavier arrows that it was related to another factor. The other option is that the arrow was so heavy it was losing enough speed by the time it passed the Chrono that it appeared to be losing energy.

What I would expect to see, is more of a velocity versus momentum balance where arrow flight is good, energy is near the theoretical maximum, and effective range is still acceptable for the shooter.

Interesting discussion though.





Sent from my Pixel 2 XL using Tapatalk

 

[Berger024]

It's all relative no matter which way you swing it. What works for someone won't always work for another. Literally called a local shop to see if they had any match-grade Axis in 300 spine yesterday and was told word for word: "Woah, no. That's a really heavy arrow for us to be dishing out. Don't think we've ever carried anything that heavy let alone the match-grades. We usually use 400 or 340 as a last resort"....

Brendan is 100% right, need to know the variables in play here

Agreed. I called a "Pro Shop" for 280 Easton FMJ's and the guy acted like I was out of my mind. I have a 30" draw length @ 67# and that was the spine Easton said to go with...A lot of pro shops out here run things like the typical employee at Cabela's, meaning you most likely know more than they do, if it's anything out of the normal.

 

[Gearqueer]

My 68# at 27.5 draw is slinging 525+ grains at 238 FPS. I will find out on animals this year if the speed is too slow, but I’m sure there are a lot of low poundage shooters and trad folks who that doesn’t bother one bit.

Pin gaps aren’t an issue for me because I’d never shoot at an animal past 60 yards (unless it’s already hit I guess).


Sent from my iPhone using Tapatalk

 

[N2TRKYS]

Agreed. I called a "Pro Shop" for 280 Easton FMJ's and the guy acted like I was out of my mind. I have a 30" draw length @ 67# and that was the spine Easton said to go with...A lot of pro shops out here run things like the typical employee at Cabela's, meaning you most likely know more than they do, if it's anything out of the normal.

He acted like that cause you were shooting fmj, not cause of the spine.

 

[N2TRKYS]

KE definitely falls off, at least, according to the GT calculator. My 406 grain arrows has more KE than my 438 grain ones.

 

[Berger024]

He acted like that cause you were shooting fmj, not cause of the spine.

Well, it wouldn't be the first time I've heard that...

 

[Greenmachine_1]

KE definitely falls off, at least, according to the GT calculator. My 406 grain arrows has more KE than my 438 grain ones.

"All models are wrong. Some models are useful."

-Unknown originator

Your calculator is wrong. If you run those two arrows through a chronograph, you will not likely notice that discrepancy.

Sent from my Pixel 2 XL using Tapatalk

 

[Mighty Mouse]

KE definitely falls off, at least, according to the GT calculator. My 406 grain arrows has more KE than my 438 grain ones.

That's very surprising. Out of curiosity, what bow/draw weight/draw length are you shooting?

 

[N2TRKYS]

"All models are wrong. Some models are useful."

-Unknown originator

Your calculator is wrong. If you run those two arrows through a chronograph, you will not likely notice that discrepancy.

Sent from my Pixel 2 XL using Tapatalk

Not my calculator. I shot my arrows through my chrono., otherwise, I wouldn’t know how fast it was shooting.

 

[N2TRKYS]

That's very surprising. Out of curiosity, what bow/draw weight/draw length are you shooting?

Hoyt Carbon Element
70# limbs that are maxed out
27.5” arrow

 

[Mighty Mouse]

Hoyt Carbon Element
70# limbs that are maxed out
27.5” arrow

What speeds are you getting with the 406 and 438 gr arrows?

 

[Greenmachine_1]

Not my calculator. I shot my arrows through my chrono., otherwise, I wouldn’t know how fast it was shooting.

So... What were the speeds or differences in K.E.?

Sent from my Pixel 2 XL using Tapatalk

 

[N2TRKYS]

What speeds are you getting with the 406 and 438 gr arrows?

406 grains @288fps

438 grains @275fps

 

[S.Clancy]

I think you should ask yourself how far you are gonna shoot before you ask about too heavy. If you're keeping your shots under 50 or even 60 yds, shooting a heavy arrow in the 230s-240s is fine. You'll just have to verify range.

 

[Mighty Mouse]

406 grains @288fps

438 grains @275fps

Very curious. Those numbers run counter to all the KE data I've gathered, although I've never tested your particular bow model. It would be interesting to try additional heavier arrows to see if the KE downtrend continues. All my testing has shown a gradual increase in KE with increasing arrow weight similar to the attached graph.