Arrow too heavy??

[DoubleLunger]

Just curious if it's possible to have too heavy of an arrow for taking tough African game such as Zebra, Gemsbok, Kudu, Eland, etc.

I've been told that heavier is better but at what point do you say that it's just too much weight and will not give you the desired effect upon impact of the tougher game mentioned above at 40 to 60 yards.

My bow is a Mathews Creed which is maxed out at 70 pounds pull with a 27.5" draw length.

Arrows are the Black Eagle "Spartans" (250 spine) with Strickland Archery "Hellix" fixed two blade single beveled 200gr broadhead.

My total weight of arrow is 582 grains with an FOC of 19%. Unsure of my feet per second and KE.

My concern right now is that my arrow would be too heavy and possibly slow down too much before making contact with tough game and not getting the penetration that I need at 40 to 60 yards.

I am also planning to upgrade my sight(possibly a Spothog brand) to be able to practice at 100 yards. Currently practicing at 60 yards.

I'm also looking to upgrade my stabilizer to something around 10" for more stability.

I'm aware that shot placement is very important and I plan to be well prepared for this.

Let me know what you guys think.

Thank you my fellow bow hunters

 

[jeff]

Your worrying too much, your set up is over kill for plains game and as far as too heavy for longer distances, it is the opposite, the lighter the arrow the faster it sheds velocity.

 

[BRICKBURN]

...............
I'm aware that shot placement is very important and I plan to be well prepared for this.
.............

This is at the top of the list. Ultimately, important.
Bullets with the wrong shot placement don't do the job properly.

Assuming an IBO of 300 for the bow it calculates out at 198 fps.
http://archerycalculator.com/estimate-bow-speed/

 

[mrpoindexter]

I agree that a heavy arrow will maintain its speed much better than a lighter arrow. 582 grains is not too heavy. There are a lot of people who shoot 650 grain arrows on plains game. I was shooting lighter arrows than you on my last plains game hunt and will be upgrading to heavier arrows before my next safari - very likely 650 grain, but certainly not less than 550. I will be shooting PG with a 70lb Mathews Halon.

 

[mrpoindexter]

Brickburn, the online archery calculators are notorious for underestimating the speed of heavy arrows.

The Mathews Creed is a 328 FPS IBO speed bow.

 

[mrpoindexter]

OK, just checked out with OnTarget2 and here is what I got:

Your dynamic spine is .279 and your arrow spine is .250 (assuming a 29" arrow shaft length and 59g insert weight to hit both the stated FOC and arrow mass). Your spine is a little stiff but in the acceptable range and I would rather have too stiff than not stiff enough.

Your velocity should actually be 242 FPS, giving you 75.8 Ft-Lbs of Kinetic Energy and 0.626 Slugs of Momentum.

 

[DoubleLunger]

This is at the top of the list. Ultimately, important.
Bullets with the wrong shot placement don't do the job properly.

Assuming an IBO of 300 for the bow it calculates out at 198 fps.
http://archerycalculator.com/estimate-bow-speed/

I believe the manufacturer website said 328 for IBO. Thanks for taking the time to give me some guidance

 

[DoubleLunger]

OK, just checked out with OnTarget2 and here is what I got:

Your dynamic spine is .279 and your arrow spine is .250 (assuming a 29" arrow shaft length and 59g insert weight to hit both the stated FOC and arrow mass). Your spine is a little stiff but in the acceptable range and I would rather have too stiff than not stiff enough.

Your velocity should actually be 242 FPS, giving you 75.8 Ft-Lbs of Kinetic Energy and 0.626 Slugs of Momentum.

If the numbers are right then it looks like I'm in the right ballpark. Thank you for getting together the information and reaching out.

According to what Black Eagle told me my inserts are a total of 56 gr and my draw length is 27.5" with an arrow shaft of 28".

 

[BRICKBURN]

Brickburn, the online archery calculators are notorious for underestimating the speed of heavy arrows.

The Mathews Creed is a 328 FPS IBO speed bow.

Any calculator is always a guesstimate.

That brings the speed up to 226 FPS.

Nothing like a chronograph to tell the truth.

 

[DoubleLunger]

Your worrying too much, your set up is over kill for plains game and as far as too heavy for longer distances, it is the opposite, the lighter the arrow the faster it sheds velocity.

Worried or just making sure I'm prepared?

 

[mrpoindexter]

Brick, the calculators do not use a real world model for estimating the change in bow efficiency. I tested my bow against the OT2 software and they matched what I was seeing with a chrono across many different weights of arrows. I would peg his velocity at 242 and expect him to be probably within a couple (1-2) FPS of that number. Calculating KE and MO is easy but estimating arrow speed isn't when they don't use a real world model to base their data on.

 

[Ryan]

There may be a point diminishing returns but out of a 70 pound modern compound using a 582 grain arrow you aren't near it. And heavier projectiles actually lose speed slower over distance compared to lighter ones. That's one of the big reasons target rifle shooters use such heavy for caliber bullets. Chuck Adams showed that back in the 80's using far less efficient bows by actually getting speed reading at distance of 60+ yards so he knew he could confidently shoot sheep that far. He could and did and your bow is the equivelant to a 85+ pound draw bow from then, far more than most anyone shot back then. You've covered all the bases, get shooting accurately and confidently now and show us some pics of your success. Good luck.

 

[jeff]

It seems to me that the opinion that larger plains game is incredibly tough stems from shots that are too far back, in the States we'r used to shooting behind the shoulder and the same shot in Africa is too far back and gives the idea that they are way tougher. Out of the 24 larger plains game that I've taken with a bow they go down quickly, no tougher than elk except for two that I shot too far back! And as for the skin be thicker, I've not see that it's thicker or tougher than comparable sized game here.

 

[DoubleLunger]

There may be a point diminishing returns but out of a 70 pound modern compound using a 582 grain arrow you aren't near it. And heavier projectiles actually lose speed slower over distance compared to lighter ones. That's one of the big reasons target rifle shooters use such heavy for caliber bullets. Chuck Adams showed that back in the 80's using far less efficient bows by actually getting speed reading at distance of 60+ yards so he knew he could confidently shoot sheep that far. He could and did and your bow is the equivelant to a 85+ pound draw bow from then, far more than most anyone shot back then. You've covered all the bases, get shooting accurately and confidently now and show us some pics of your success. Good luck.

Great insight my friend. I'm shooting every day now. I will post pics upon my return. Thanks for the info

 

[mrpoindexter]

It seems to me that the opinion that larger plains game is incredibly tough stems from shots that are too far back, in the States we'r used to shooting behind the shoulder and the same shot in Africa is too far back and gives the idea that they are way tougher. Out of the 24 larger plains game that I've taken with a bow they go down quickly, no tougher than elk except for two that I shot too far back! And as for the skin be thicker, I've not see that it's thicker or tougher than comparable sized game here.

I do think they are tough. I have shot a couple animals that were right on the money but didn't get a lot of penetration. As for skin thickness, that is only part of the equation. I do think these animals are tougher because they endure a much higher predatory load than animals in North America have endured through much of their evolution (an opinion, but it feels right to me). That we have seen their vitals to be father forward than the NA game shows there has been a difference in the animals and it is likely from some evolutionary cause that may well have made them tougher than the NA game.

 

[jeff]

I think flesh is flesh and the flesh of a zebra is no tougher than the flesh of a elk, meat is meat! American game used to have a lot predation grizzly, black bear, wolves, coyotes and cougar. I have taken close to 90 big game animals with a bow, 14 north american and 13 African species, I say that not to brag but to put some experience to my opinion, and that's all it is it's my opinion. I don't think ribs are harder to cut on plains game than similar sized American game. Shoulder shots, elbow shots, too high or too low or too far back that's where problems start.

 

[kathy]

Double Lunger, you are a brave man to go to Africa and take shots @ 40 to 60 yards , if you draw blood you have just bought that animal . my opinion. I don't take shots on N.A. game past 25 yards much less African game, it is up close and personal for me.
Now on with the question, I want at least a 600 grain or heaver arrow. I do practice out to 40 yards and the arrow sticks deep in my target ,couldn't tell you past 40.
I would think you will have plenty of momentum out to 60 yards to kill any of the planes game you mentioned , if they stand still that long. Forrest

 

[mrpoindexter]

I modeled your arrow again and got the weight to your 582 grains, but based on the numbers for the point and insert, it only really works out if you are using a Nockturnal or have some heavy fletching/wraps.

At 582 grains, it looks like your FOC is closer to 18% (17.81% according to the way I have it modeled). That would put the speed at 240.45 FPS. Taking that as a starting point, I mapped out the ballistics to get the KE and MO at ranges out to 60 yards.

Range Velocity KE MO
0 yds 240.45 74.70 0.621
10 yds 238.68 73.61 0.6168
20 yds 236.92 72.53 0.6123
30 yds 235.18 71.47 0.6078
40 yds 233.45 70.42 0.6033
50 yds 231.73 69.39 0.5989
60 yds 230.03 68.47 0.5949 (Time of flight: 0.7587 seconds!!)

The time of flight starts to be an issue as 3/4 of a second is a long time for an animal to stand perfectly still. You have plenty of power to rip through an animal. He just needs to stay put. Just to see how it looked, I ran the numbers at 120 yards. Vel 220.06, KE 62.58, MO 0.5687, but time of flight is 1.5381 seconds! You can kill it, but hitting it is the challenge.

 

[navar]

Your set up is Ok for the hunt you going on. Just make sure you hit the buck in the right place !!!!

 

[navar]

Your set up is Ok for the hunt you going on. Just make sure you hit the buck in the right place !!!!