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Author Topic: Effective velocity  (Read 1444 times)

Offline CP

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Re: Effective velocity
« Reply #15 on: September 08, 2017, 07:12:58 AM »
Here's a long winded but good read on the subject:

http://www.ballisticstudies.com/Knowledgebase/Effective+Game+Killing.html


Offline theleo

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Re: Effective velocity
« Reply #16 on: September 08, 2017, 07:28:12 AM »
There's no hard and fast rule. You need enough velocity for the bullet to expand and enough energy that it can reach the vitals. Some bullets need more velocity (like Barnes X bullets) while others don't require as much while others need less (like Ballistic Tips or Bergers). The best thing to do is call and ask the manufacture instead of listening to us internet experts. Personally my next elk tag, whenever I draw it, I'll be using a load that generates 1,570 ft/lb at the muzzle and will shoot it out to 300 yards, hopefully, (the rifle is a work in progress) where it will only generate 814 ft/lb of energy. Internet experts will call that down rite unethical, guys that actually have a clue, now that with the rite bullet it will topple an elk just fine.

Offline Magnum_Willys

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Re: Effective velocity
« Reply #17 on: September 08, 2017, 07:38:15 AM »
Yep York's testing turned me away from Bergers completely. I know blasphemy - but I like to minimize the risk of losing game.   Im pretty confident at least 1500+ ft lbs and 1700 fps with SMK's will get the job done.

Offline birddogdad

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Re: Effective velocity
« Reply #18 on: September 08, 2017, 07:47:22 AM »
not sure if velocity is what you should ask, rather calculated energy down range may be better with all the other variables.. staying supersonic is necessary for the traj. math to remain accurate and the others can vary so much that its more opinion than anything else..

Consider this thought:
if you take a 45cal pistol and put it against the side of a deer and shoot directly into vitals, will it kill it? Elk? if you think so, look at the data table for muzzle energy for the 45 and then bounce with your rifle ballistics table.. that would be the absolute worst I would argue as limits, and frankly would say that is too far but math would support effective kill if you hit effective kill area on game... this is just an example. the further out you go the angle of incoming projectile will affect how vitals are impacted as well.
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Offline Magnum_Willys

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Re: Effective velocity
« Reply #19 on: September 08, 2017, 07:55:46 AM »
Interesting thought Birddog. Thats only 400-500 ft lbs.

Offline birddogdad

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Re: Effective velocity
« Reply #20 on: September 08, 2017, 08:04:34 AM »
Interesting thought Birddog. Thats only 400-500 ft lbs.

just a spitball but I feel its fairly accurate, though not recommended for the "standard" shooter..
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Offline baker5150

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Re: Effective velocity
« Reply #21 on: September 08, 2017, 08:49:09 AM »
Great info guys, thanks.

Offline yakimanoob

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Re: Effective velocity
« Reply #22 on: September 08, 2017, 09:17:42 AM »
Great discussion (it's nice to read a thread on this subject that doesn't turn into a flame war!).  I got the same 1800 fps minimum from Berger when I talked to their rep, so that's apparently the industry standard.  Anyone heard from Hornady on the subject? 

It seems a bit counterintuitive, but Berger and Hornady have both told me that it's velocity, not energy, that should be used to gauge how the bullet will expand. Not sure exactly why this is the consensus, but I haven't do any testing myself so  :dunno:


Baker, another thought to keep in mind is that, especially at long ranges, you should be using the G7 ballistic coefficients instead of the G1.  The G1 BC of a modern boat-tail hunting bullet changes with velocity, and it's impossible for the models to predict those changes exactly.  The G7 BC is constant (or close enough to constant, anyway) at all relevant shooting velocities.  Most high-quality hunting bullets will have a G7 BC listed in the specs, and all the good calculators will allow you to specify that you're using G7 (although sometimes you have to open the advanced features to do so).

Offline h20hunter

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Re: Effective velocity
« Reply #23 on: September 08, 2017, 09:25:08 AM »
Velocity provides the oompf for expansion which in turn results in energy into the target. Like mentioned, its a dance between velocity, expansion aka bullet performance, and the resulting trasfer of energy. I find it fascinating.

Offline Bob33

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Re: Effective velocity
« Reply #24 on: September 08, 2017, 09:33:07 AM »
Read the article that CP referenced. Killing efficiency is more than simply velocity or energy.

A 100 mph baseball has about 1700 ft/lbs of energy but isn't likely to kill an elk.

Here's a long winded but good read on the subject:

http://www.ballisticstudies.com/Knowledgebase/Effective+Game+Killing.html
Nature. It's cheaper than therapy.

Offline 7mmfan

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Re: Effective velocity
« Reply #25 on: September 08, 2017, 09:38:57 AM »
Velocity provides the oompf for expansion which in turn results in energy into the target. Like mentioned, its a dance between velocity, expansion aka bullet performance, and the resulting trasfer of energy. I find it fascinating.

This. And Bob33's comment is spot as well. The larger/heavier the object, the more energy it is going to carry regardless of its velocity. You need that velocity to provide proper penetration and expansion to transfer that retained energy into the animal to ensure a good ethical kill.
I hunt, therefore I am.... I fish, therefore I lie.

Offline h20hunter

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Re: Effective velocity
« Reply #26 on: September 08, 2017, 09:51:50 AM »
Perfect example....your 7mm and my 308. Same distance, similar bullet size,  NOT the same impact results. Yours put the hurt on for sure.

Offline 7mmfan

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Re: Effective velocity
« Reply #27 on: September 08, 2017, 09:58:52 AM »
It packs a wallop, that's for sure. Ask your  steel, it'll tell you. That is, if it will still talk to you after letting my dad and I shoot it.
I hunt, therefore I am.... I fish, therefore I lie.

Offline h20hunter

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Re: Effective velocity
« Reply #28 on: September 08, 2017, 10:04:55 AM »
One younger shooter last weekend snuck a 223 round between the ear and the bolt. Sheared the bolt clean in half. Very cool. You could hear the difference in impact timing as well. Those few extra hundred fps make a difference. The steel is good, we have an understanding. I gave two plates a fresh coat if orange just this morning.

Offline yakimanoob

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Re: Effective velocity
« Reply #29 on: September 08, 2017, 10:11:52 AM »
Velocity provides the oompf for expansion which in turn results in energy into the target. Like mentioned, its a dance between velocity, expansion aka bullet performance, and the resulting trasfer of energy. I find it fascinating.
I'm with ya on finding it fascinating.  I don't even have a long-range setup (nor the necessary skills to think about shooting past 350 or so) but I'm so much of a nerd I still like to learn about it (cf. the thread on the Coriolis effect in virtual campfire  :chuckle:).

There's no way to untangle velocity from energy -- it's not as if mass changes for a bullet in flight, so velocity is really the only variable in external ballistics anyway.  But it's literally energy that makes the bullet deform/expand so you think that would be the baseline metric that's used.  But apparently velocity is more handy?   :dunno:

 

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