# Min amout of knockdown force at 700yrds?

Discussion in 'Deer Hunting' started by JWR07, Nov 6, 2009.

1. ### JWR07Member

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What is the min amount of force to kill a 200 -250lb deer at 700 yards quickly?

2. ### Guy MWell-Known Member

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I'm not a big one to try and put numbers to something like that. I think it's an attempt to use mathematics on something that is really tough to quantify.

I've seen no difference in killing power on deer with any of several different cartridges. For instance the little .243 Win & 6mm Rem have caused instant death, same as far more powerful rifles... Instant death is pretty hard to trump. It doesn't get more instant when more power is applied.

Put a good quality expanding bullet into the heart and lungs, with enough velocity to initiate expansion, and you've got venison. They're pretty easy to kill. Very difficult to sustain life when the lungs are shredded and the heart perforated.

Then again, I haven't shot one at 700 yards yet.

I've read a lot of different theories about killing power, expressed in foot-lbs of energy for various size animals at various ranges... After seeing quite a few deer killed over the years, I'm not so sure the numerical theories make a lot of sense for determining "knockdown" or "killing" power. I'm also not sure "knockdown force" is a really good term. In simple physics, if your rifle generates enough force to knock down a deer, it's also going to knock you down when you shoot it... At least that's the way I remember my High School physics from about a million years ago!

FWIW, Guy

3. ### JWR07Member

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I understand what you ae saying. I was just trying to find a baseline number for knockdown energy in order to humanely make a quick kill. I thought may 1000lbs of energy would be the min. Would you agree with this. Given we are using quality bullets.

4. ### trebarkWell-Known Member

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Regardless of range, the conventional wisdom says 1000lbs of energy to kill deer and 1500lbs for elk. All that energy means nothing with the wrong bullet or a poorly placed shot.

5. ### JWR07Member

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Thanks that is kinda the number I was thinking would be min. If so then a 6.5x270wsm and a 270wsm should both be good for 700 yards given both retain 1000 lbs of KDP at that range.

6. ### kcebcjWell-Known Member

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Also make sure your bullet of choice retains the velocity needed for proper expansion. With some calibers itâ€™s the velocity that determines maximum range for a given animal.

7. ### JWR07Member

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I decided to use a 270wsm with 140gr accubonds. Iam going to push it at 3150fps. Now given thevelocity and Nosler published BC (496) and using hanloads.com ballistic calculator I should have 1969fps and KDE of 1205 at 700 yards. I think that even though the numbers are just computer numbers this should be ok for whitetails out to 700yrds, boar out to 300yrds and bear (southeastern black) out to 150 to 200yrds.

8. ### justgotoWell-Known Member

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Exactly! It would be the same at 100 or 3000.

9. ### trebarkWell-Known Member

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1970fps....1205lbs...you're good to go.

10. ### bigngreenWell-Known Member

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I shot a mule deer buck at 340yds with the 140 Accubond starting out at 3340fps and there is no doubt that I would shoot any animal in the lower 48 with it after seeing the terminal performance and recovering the bullet out of the dirt.
At the speed I'm running them I'm keeping them to around 800yrds, I'm a little unsure if the Accubond will open up enough to deliver that energy so I am working with the 140 Berger also. It shoots 2.5 inches higher at 100yrd zero than my Accubond load so it works perfect.
The bullet speed and construction will determine you max range, I've shoot quit a few deer out at 350-400 yrds with a cal that only has 600-800 of energy and it did a wonderful job but the bullets were delivering 100% of that energy in the vitals, if I had shot a bonded bullet they would have not delivered hardly any energy and just poked through.
Decided on a particulat rifle yet?gun)

11. ### JWR07Member

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The rifle is going to be custom built 270wsm by Clay Spencer of Spencer Barrels. Here are the specs.

Action - Kelbly Atlas Repeater
Trigger - Shilen standard (set at 2lbs)
Recoil lug - Holland's
Barrel - Spencer 1-10 twist in (Shilen #6 LT varmint profile) 24"
Stock - MCM Tac Hunter w/ edge tech
Bottom Metal - HS detach mag
Base - Kelbly's
Rings - Kelbly's double screw
Scope - Leupold 6.5x20x40lr
I can't wait till this rifle is done.

12. ### trebarkWell-Known Member

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This opens up a whole new conversation...why 270WSM? 270 bullet selection and BC are not great. The 7mm WSM I would think would be a better choice. Great bullet selection and great BCs

13. ### JWR07Member

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I choose a 270wsm becasue I already have lots of .277 bullets for a 270ihmsa. This is bacisly a 300 savage with the shoulder moved back. I am getting about 2500 with it out of a 22" barrel with 140gr bullets. This is my go to rifle for light weight carrying. But I need a rifle for stand hunting over a power line right of way that I have clear shots out to approx 700 to 800 yards. Also in the 7mm vs 270 debate I have always used a 277 cal never seen the need for a 7mm.

14. ### JWR07Member

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FYI just running the numbers on a 7mm 140 accubond vs a .277 140gr accubond, the numbers favor the .277 if both use a velocity of 3150. If we go to 3186 for the 277 and 3200 for the 7 the numbers still favor the 277with 1814fps and 1023fpe at 820yrds. The 7 @ 820 is 1798fps and 1005fpe. So why not get the most with a 140gr bullet. (all numbers are using Nosler numbers in Hanloads.com ballistic calculator) FYI even if you run the 7mm at noslers max it still comes up 1810fps and 1018fpe.

140gr .277 BC .496 max & 3186 max fps
140gr .844 BC .485 max & 3218 max fps

per Nosler "minimum velocities for reliable expansion 1800fps"

Last edited: Nov 8, 2009