KE / Momentum for Medium Plains Game?

[SikaMDhunter]

What's your draw length? That plays a major part as well

 

[mdwest]

What's your draw length? That plays a major part as well

30” (6’4” with orangutan arms)…

 

[SikaMDhunter]

218 fps, 67.1 ft-lbs (ke), 0.62 slug-ft/s (M)
Victory VForce Gamer is 9.7 grains an inch
20% FOC is nice

sounds real good. I would upgrade my broadheads if anything. Like others said single bevel, tanto tip is the way to go (iron will/tuffhead, Grizzlystik). If you wanna keep going down the hole more, see if your bow bare shaft rotates left or right. Make sure your fletching and single bevel match the natural rotation.

 

[mdwest]

I cant seem to help myself... further and further down the rabbit hole I go...

So... 1 month out from getting on a plane... I have changed literally EVERYTHING lol..

Picked up a new (to me) bow.. a 2020 Hoyt Axius Ultra... I really didnt intend on doing that.. but.. it was at a price that made me feel like I was stealing it.. and flagship bows with a 30-32" adjustable DL cam already installed, that are left handed, that are in near new condition (I would bet this bow has less than 100 arrows through it based on its condition) that can be had for less than $500 delivered to your door dont come along every day.. So... I got the checkbook out and just made it happen..

Which then compelled me to start all over with arrows lol...

Im now shooting Easton FMJ's (250 spine... 11.5 GPI), with a 75 gr Easton 1/2 outsert, Which brings the arrows in just a little over 605 gr with a 150 gr broadhead.. I havent chrono'd the arrow yet.. but Im guessing Im getting about 245 FPS.. Which should give me a momentum value of about .658.. A decent improvement over the PSE shooting the victory arrows I was previously working with..

Im still tweaking the bow, getting everything tuned up, the single pin sight dialed in, etc.. once I get it where I want it I'll put it on the chronograph and confirm/deny my suspicions..

I dont have a lot of time to train with it, but I'm already feeling a lot more confident with this rig.. the draw cycle is A LOT smoother.. the bow balances better overall.. its got a much faster IBO rating.. etc etc.... and I still should be able to easily get 300-400 shots down range with it before I go wheels up in a month... So, I think I'm good to go...

 

[mdwest]

I think I finally hit the sweet spot and can quit obsessing… Ashby should be proud lol…

I’ve ended up with a 655 grain arrow (bumped up to a 200gr broad head) with an FOC of 20.11.

The new bow reliably flings that stick at 240 fps..

That gives me a KE value of 83.82, and a momentum value of .698

I’m shooting Crimson Talon single bevel broad heads (200gr cleavers)…

Other than a Cape buffalo, there’s nothing that walks the property at Bos en Dal Safaris that shouldn’t drop with this rig (assuming I do my part and put the arrow where it belongs)…

I’d still like to improve my shooting skills a bit… I can consistently keep a 3” group at 20 yards and about a 5” group at 30… which certainly doesn’t give me Ivanhoe or Robin Hood status… but should get the job done… I think if I just keep shooting 20-30 arrows a day, 5x days a week, for the next 4 weeks, those groups will improve (still very much getting used to the new rig, new arrows, etc)… I plan on taking it out to a range where I can get 40-70 yard shot practice in once s week until we leave as well…

 

[SikaMDhunter]

Good set up. What kind of release are you using?

 

[mdwest]

Its an older Tru-Fire wrist strap, trigger type release..

Ive been looking to upgrade that as well and have toyed with a couple of thumb releases from spot hogg, scott, etc.. but havent really settled in on anything yet... but probably wont do that until after we're back from South Africa and start practicing for deer season (will likely drop to a little less heavy, little faster arrow for TX deer as well)..

 

[SikaMDhunter]

I'd suggest a back tension to improve accuracy. I enjoy the feel of a wrist strap so I got the Scott Archery Verge Hybrid Hinge. It's a back tension release but still feels like an older wrist strap

 

[rookhawk]

Since penetration is the name of the game, here are all the tricks we did to get pass throughs on game starting at 27lb draw weight and 21" draw length. Obviously, that is extremely underpowered but the right tools made it work flawlessly. It's the same principles a feeble, puny human drawing 100lbs at 31" struggles with when trying to shoot an elephant. Same-Same.

1.) Incredibly high quality cut-on-contact broadheads
2.) Razor, Razor sharp hand stropped blades
3.) Single bevels so they require less effort to cut due to fewer cutting surfaces than a double bevel
4.) No bleeders (if you have the power, go for it)
5.) As thin and light of a shaft as you can find. I'm a big fan of "shitty arrow shafts"
6.) As good of an insert/outsert system as money can buy, ethics archery or other. These should be the same diameter or less than the broadhead ferrule
7.) Wax the shafts with armor all crystal car wax. It smells, so do it way ahead of the hunt to deplete smell. A waxed shaft fills micro pores and reduces drag, it also sheds water which can result in better accuracy than an arrow with a drip on it causing asymmetry.
8.) Build for heavy FOC, hence "shitty shafts" are your ally. When the shafts are light enough, you're just shooting bullets with a string attached to the back. The integrity comes from the broadhead and the insert/outsert system
9.) Razr feathers are less durable than vanes, but they are more likely to pass through. An arrow 90% through an animal is still plugging half the holes, making tracking harder while reducing blood loss and mortality.
10,) Select a tanto tip broadhead. It is less likely to curl and more likely to break bone.
11.) Don't use illuminated nocks, they erode FOC
12.) Shorter arrows have less drag and are less likely to pass through. Remove shaft length and make up with it by heavier insert/outsert/broadhead upping FOC and shortening the length of the arrow.
13,) Use rubbing alcohol to remove arrow decals. They introduce minute amounts of drag as well.
14.) Use a thin shaft, 4mm ideally if they tune, 5mm worst-case.


Obviously all the accuracy things too, index your broadheads to the spine. Have the cock vane on the spine.

Building an Africa arrow is all about ultra anal retentiveness. You'll note that all the things I list above aren't about money, you probably are spending $100-$120 an arrow anyway. Its about the details. Stacking tiny improvements to penetration end up making a big difference. You might argue "its minuscule, like 2% gains". YES. 14 things above with minuscule 2% gains is 28% better in total.

 

[SikaMDhunter]

Since penetration is the name of the game, here are all the tricks we did to get pass throughs on game starting at 27lb draw weight and 21" draw length. Obviously, that is extremely underpowered but the right tools made it work flawlessly. It's the same principles a feeble, puny human drawing 100lbs at 31" struggles with when trying to shoot an elephant. Same-Same.

1.) Incredibly high quality cut-on-contact broadheads
2.) Razor, Razor sharp hand stropped blades
3.) Single bevels so they require less effort to cut due to fewer cutting surfaces than a double bevel
4.) No bleeders (if you have the power, go for it)
5.) As thin and light of a shaft as you can find. I'm a big fan of "shitty arrow shafts"
6.) As good of an insert/outsert system as money can buy, ethics archery or other. These should be the same diameter or less than the broadhead ferrule
7.) Wax the shafts with armor all crystal car wax. It smells, so do it way ahead of the hunt to deplete smell. A waxed shaft fills micro pores and reduces drag, it also sheds water which can result in better accuracy than an arrow with a drip on it causing asymmetry.
8.) Build for heavy FOC, hence "shitty shafts" are your ally. When the shafts are light enough, you're just shooting bullets with a string attached to the back. The integrity comes from the broadhead and the insert/outsert system
9.) Razr feathers are less durable than vanes, but they are more likely to pass through. An arrow 90% through an animal is still plugging half the holes, making tracking harder while reducing blood loss and mortality.
10,) Select a tanto tip broadhead. It is less likely to curl and more likely to break bone.
11.) Don't use illuminated nocks, they erode FOC
12.) Shorter arrows have less drag and are less likely to pass through. Remove shaft length and make up with it by heavier insert/outsert/broadhead upping FOC and shortening the length of the arrow.
13,) Use rubbing alcohol to remove arrow decals. They introduce minute amounts of drag as well.
14.) Use a thin shaft, 4mm ideally if they tune, 5mm worst-case.


Obviously all the accuracy things too, index your broadheads to the spine. Have the cock vane on the spine.

Building an Africa arrow is all about ultra anal retentiveness. You'll note that all the things I list above aren't about money, you probably are spending $100-$120 an arrow anyway. Its about the details. Stacking tiny improvements to penetration end up making a big difference. You might argue "its minuscule, like 2% gains". YES. 14 things above with minuscule 2% gains is 28% better in total.

Agree with almost everything. I'd replace armor all with Slick Stick from Sirius archery.

I also wouldn't use a shitty shaft. Solid carbon with a stiff spine.

But you're absolutely on point.

 

[rookhawk]

Agree with almost everything. I'd replace armor all with Slick Stick from Sirius archery.

I also wouldn't use a shitty shaft. Solid carbon with a stiff spine.

But you're absolutely on point.

Fine with your choice of "lube"

You miss my point with "shitty shaft". "Good shafts" are generally stupid things that steal FOC like FMJs or way overbuilt shafts from Alaska Archery. I don't want the shaft to be fort-knox strong, I want the broadhead/insert/outsert to be the integrity keeper, the carbon should be lightweight and if properly affixed to the head, the system has integrity. Heavy shafts rob FOC, the shaft is just a string to hold the bullet when flying.

 

[SikaMDhunter]

Fine with your choice of "lube"

You miss my point with "shitty shaft". "Good shafts" are generally stupid things that steal FOC like FMJs or way overbuilt shafts from Alaska Archery. I don't want the shaft to be fort-knox strong, I want the broadhead/insert/outsert to be the integrity keeper, the carbon should be lightweight and if properly affixed to the head, the system has integrity. Heavy shafts rob FOC, the shaft is just a string to hold the bullet when flying.

Fair point. I prefer shafts from companies that specifically go for foc. I think the Ashby foundation and arrows that follow this idea are the way to go. I hate fmj

 

[rookhawk]

Agree with almost everything. I'd replace armor all with Slick Stick from Sirius archery.

I also wouldn't use a shitty shaft. Solid carbon with a stiff spine.

But you're absolutely on point.

Post script on "Shitty Shafts". I almost hate to mention it because its contentious and the testing is not well vetted. There are competing theories on shaft diameter.

1.) Face value logic, the thinner the shaft, the less likely to rub on bone, less wind deflection, less surface area to introduce drag during penetration.

And the anecodotal:

2.) Thinner arrows are reporting less penetration on occasion than thicker. How can this be, its obvious point 1 above is logical?! Dynamic spine. When the arrow hits the animal initial, it stops, the arrow flexes, then it begins boring into the animal. The thicker walled shafts (5mm) may have less flex upon initial impact due to the larger wall circumference at a given weight than its ultra thin (4mm) equivalent.

My son is shooting "shitty shafts", Easton 5mm Underarmor labeled ones we got on sale. The 4mm Axis at his spine and total arrow weight had less penetration.

My takeaway: You've got to test this, at some point the logical benefits of thin shafts due to point 1 may have less benefit than the reaction and recovery of flexing upon impact noted in point 2 above.

Ashby and others have another anecdote they are trying to assign causation to at present. They are finding ultra heavy arrow / FOC builds on buffalo from 60lb bows were getting better penetration and pass throughs in their testing than 70 and 80lb bows. Why the hell is this because it defies logic?! It may be that same effect of higher power upon impact causing more initial flex of the arrow that slows down the arrow and creates more resistance when burrowing through the animal.

Too many variables and I certainly won't hang my hat on these anecdotes, but something is afoot.

 

[SikaMDhunter]

I shoot 4mm. Came to this after going to 5mm. At first glance I didn't think they'd hold up. 4mm is a powerful shaft.

Ashby findings is based on trad bows but the foundation is conducting tests with recurve.

 

[mdwest]

Since penetration is the name of the game, here are all the tricks we did to get pass throughs on game starting at 27lb draw weight and 21" draw length. Obviously, that is extremely underpowered but the right tools made it work flawlessly. It's the same principles a feeble, puny human drawing 100lbs at 31" struggles with when trying to shoot an elephant. Same-Same.

1.) Incredibly high quality cut-on-contact broadheads
2.) Razor, Razor sharp hand stropped blades
3.) Single bevels so they require less effort to cut due to fewer cutting surfaces than a double bevel
4.) No bleeders (if you have the power, go for it)
5.) As thin and light of a shaft as you can find. I'm a big fan of "shitty arrow shafts"
6.) As good of an insert/outsert system as money can buy, ethics archery or other. These should be the same diameter or less than the broadhead ferrule
7.) Wax the shafts with armor all crystal car wax. It smells, so do it way ahead of the hunt to deplete smell. A waxed shaft fills micro pores and reduces drag, it also sheds water which can result in better accuracy than an arrow with a drip on it causing asymmetry.
8.) Build for heavy FOC, hence "shitty shafts" are your ally. When the shafts are light enough, you're just shooting bullets with a string attached to the back. The integrity comes from the broadhead and the insert/outsert system
9.) Razr feathers are less durable than vanes, but they are more likely to pass through. An arrow 90% through an animal is still plugging half the holes, making tracking harder while reducing blood loss and mortality.
10,) Select a tanto tip broadhead. It is less likely to curl and more likely to break bone.
11.) Don't use illuminated nocks, they erode FOC
12.) Shorter arrows have less drag and are less likely to pass through. Remove shaft length and make up with it by heavier insert/outsert/broadhead upping FOC and shortening the length of the arrow.
13,) Use rubbing alcohol to remove arrow decals. They introduce minute amounts of drag as well.
14.) Use a thin shaft, 4mm ideally if they tune, 5mm worst-case.


Obviously all the accuracy things too, index your broadheads to the spine. Have the cock vane on the spine.

Building an Africa arrow is all about ultra anal retentiveness. You'll note that all the things I list above aren't about money, you probably are spending $100-$120 an arrow anyway. Its about the details. Stacking tiny improvements to penetration end up making a big difference. You might argue "its minuscule, like 2% gains". YES. 14 things above with minuscule 2% gains is 28% better in total.

Ive hit most of the 14 above, or gotten relatively close with my arrow build.. although I did let the guy at Scheels talk me into the dreaded 5mm FMJ for a shaft (was trying to get to 650gr .. and even with a 200 gr broadhead and a 75 gr half out insert that was the only shaft he had that would get me even close..

I ended up with a 30" 5mm FMJ shaft (31" DL on the current bow), with a 75 gr easton steel half out insert, standard easton nock, with AAE Max 3" low profile vanes (helical), and 200gr Crimson Talon Cleaver single bevel broadheads.. I trusted the guy building the arrows to do a good job, but verified once I got home and measured each one (all are exactly the same OAL.. and all weigh +/- 1 gr of each other (not too shabby considering we're talking an arrow with an OAL length greater than 32" once you slap the nock, insert, and broadhead on it and take in all of the different items that can have variables..

Avg arrow weight is 655gr.. FOC of 20.11.. with the bow set to 70lb draw and a 31" draw length, its flinging those arrows right at 240 fps.. providing a KE value of 83.82 and a momentum value of .698...

All broadheads have been stropped on a leather strop block and have a razors edge on them.. they are single bevel 2 blade (no bleeders) with tanto tips (also made less than 15 miles from my house which I thought is pretty cool.. love supporting a small, local business that is making a quality product that seems to be getting some really good reviews ( @Bowhuntr64 has reviewed a couple of CT broadheads.. they seem to do very well in his testing as well)..

Hadnt thought about waxing the shafts... thats a good idea.. definitely going to give that a go over the weekend and see how things turn out..

 

[mdwest]

Soooooo... some more archery knowledge is needed...

My wife is now interested in taking her bow with her on this trip..

She isnt pulling a lot of weight.. and her draw length is very short..

What we're looking at is.. 25" DL, 43.5 LB draw.. on a 330 FPS IBO bow (Matthews Avail)..

Her arrows are equally small.. albeit a good bit heavy and a good FOC for what they are.. She's shooting 24.5" (carbon to carbon) FMJ's with a 75gr half out and a 150gr broadhead.. total arrow weight is 506 gr.. FOC is 17.3...

Speed is pretty slow.. She's getting about 190 FPS with those heavy (for her) arrows...

Thats giving her about 40.52 KE and .427 Momentum..

I'm ASSUMING thats plenty for smallish PG (impala, blesbok, warthogs, etc).. and might even be enough for something like a nyala.. but Im thinking anything bigger or heartier like a wildebeest, zebra, etc should probably be avoided...

Its possible she could get the draw weight up another couple of pounds between now and the time we depart.. but I dont think another pound or two is going to increase the speed enough to make much of a material difference and think its probably best just to leave everything alone and let he continue to improve skills and confidence with daily shooting until we get there...

The good news is.. shes actually a much better bow shot than I am.. she's pretty consistent with 2" or smaller groups at 20 yards.. 3" or smaller groups at 30 yards, etc..

Im also thinking she'll likely limit shots to 20 yards and not try anything any further than that..

She's shooting 2 blade, fixed, cut on contact broadheads..

Ive got a little bit of concern about "jumping the string" with the slow speed.. and a little bit concerned about penetration with the low momentum rating..

All that said.. an average recurve or longbow speed is about 150-200 FPS.. and folks have killed lots of plains game over the centuries with recurves and long bows..

thoughts?

 

[SikaMDhunter]

Ive hit most of the 14 above, or gotten relatively close with my arrow build.. although I did let the guy at Scheels talk me into the dreaded 5mm FMJ for a shaft (was trying to get to 650gr .. and even with a 200 gr broadhead and a 75 gr half out insert that was the only shaft he had that would get me even close..

I ended up with a 30" 5mm FMJ shaft (31" DL on the current bow), with a 75 gr easton steel half out insert, standard easton nock, with AAE Max 3" low profile vanes (helical), and 200gr Crimson Talon Cleaver single bevel broadheads.. I trusted the guy building the arrows to do a good job, but verified once I got home and measured each one (all are exactly the same OAL.. and all weigh +/- 1 gr of each other (not too shabby considering we're talking an arrow with an OAL length greater than 32" once you slap the nock, insert, and broadhead on it and take in all of the different items that can have variables..

Avg arrow weight is 655gr.. FOC of 20.11.. with the bow set to 70lb draw and a 31" draw length, its flinging those arrows right at 240 fps.. providing a KE value of 83.82 and a momentum value of .698...

All broadheads have been stropped on a leather strop block and have a razors edge on them.. they are single bevel 2 blade (no bleeders) with tanto tips (also made less than 15 miles from my house which I thought is pretty cool.. love supporting a small, local business that is making a quality product that seems to be getting some really good reviews ( @Bowhuntr64 has reviewed a couple of CT broadheads.. they seem to do very well in his testing as well)..

Hadnt thought about waxing the shafts... thats a good idea.. definitely going to give that a go over the weekend and see how things turn out..

Are you getting your speed from a chronograph or using some equation?

 

[SikaMDhunter]

Soooooo... some more archery knowledge is needed...

My wife is now interested in taking her bow with her on this trip..

She isnt pulling a lot of weight.. and her draw length is very short..

What we're looking at is.. 25" DL, 43.5 LB draw.. on a 330 FPS IBO bow (Matthews Avail)..

Her arrows are equally small.. albeit a good bit heavy and a good FOC for what they are.. She's shooting 24.5" (carbon to carbon) FMJ's with a 75gr half out and a 150gr broadhead.. total arrow weight is 506 gr.. FOC is 17.3...

Speed is pretty slow.. She's getting about 190 FPS with those heavy (for her) arrows...

Thats giving her about 40.52 KE and .427 Momentum..

I'm ASSUMING thats plenty for smallish PG (impala, blesbok, warthogs, etc).. and might even be enough for something like a nyala.. but Im thinking anything bigger or heartier like a wildebeest, zebra, etc should probably be avoided...

Its possible she could get the draw weight up another couple of pounds between now and the time we depart.. but I dont think another pound or two is going to increase the speed enough to make much of a material difference and think its probably best just to leave everything alone and let he continue to improve skills and confidence with daily shooting until we get there...

The good news is.. shes actually a much better bow shot than I am.. she's pretty consistent with 2" or smaller groups at 20 yards.. 3" or smaller groups at 30 yards, etc..

Im also thinking she'll likely limit shots to 20 yards and not try anything any further than that..

She's shooting 2 blade, fixed, cut on contact broadheads..

Ive got a little bit of concern about "jumping the string" with the slow speed.. and a little bit concerned about penetration with the low momentum rating..

All that said.. an average recurve or longbow speed is about 150-200 FPS.. and folks have killed lots of plains game over the centuries with recurves and long bows..

thoughts?

Ashby foundation has 12 penetration factors. These factors were found in decades of tests with trad bows. You're wife's bow is more comparable to those then a too of the line carbon bow today. So this may help out with her set up.

1. Structural integrity of the arrow system
2. Arrow flight
3. Arrow weight forward of center
4. Mechanical advantage
5. Shaft diameter
6. Arrow mass
7. Blade edge finish
8. Shaft profile
9. Broadhead/Arrow silhouette
10. You're off edge bevel
11. Tip design
12. Arrow Mass above the heavy bone threshold

You can read this finding if the Ashby foundation about halfway down this article. https://www.ashbybowhunting.org/get-started

 

[mdwest]

Are you getting your speed from a chronograph or using some equation?

ProChrono chronograph

 

[joker2400]

I think @rookhawk has posted his son’s setup somewhere on the form and IIRC it’s pretty similar.

However, if I were build an arrow for her I’d look for a .204 shaft @ 7 gpi +\- then tip it with an ethics outsert system of ~200 grains and 150 grain 2 blade single bevel heads. You can flip flop the head and outsert weights too