Ballistics

[Ultradog MN]

Both my hunting buddy and I use .270 rifles. Both of us took nice big does this year.
What was interesting is that neither of our bullets exited the deer. The deer took the full impact and all that inertia. Must be pretty big whallop at 70 to 100 yards. His knocked her clean off her feet. Mine ran - at least 350 yards afterwards.
I understand that modern rifle shells are designed to do just that - expand/fragment and induce maximum damage before/without exiting.
I suppose I could look it up how many foot lbs of force that must have been. But folks here have a way of putting things into layman's terms that are easier to make sense of.
How big of an impact is that? How many horsepower?
More than a man could produce? With an 8 lb sledgehammer swung over his head? More than a home run ball off a good batter?
Just trying to put ballistics into an everyday unit of measure here if that helps.
Thanks

 

[dabees]

I can't answer the ballistics problem but I use 300 Savage 150gr core-lokt and only had one round that didn't exit. It was last hunt I could make that year so I took a going straight away shot. It entered within 1 inch of the existing "exit Hole"and stopped in the neck(found the perfectly musroomed round while field dressing)only slightly nicked one ham and back strap. I dropped him off at the slughter house where mom worked with instructions for her to state the work order. Got a call from mom in a couple of days asking "did you smother that deer or find him dead from natural cause". BTW I'm not that good,it just worked out that way.

 

[dlplost]

150g Bullet at 2,800 fps = 2,610 ft/lb
160g Bullet at 2,800 fps = 2,784 ft/lb
170g Bullet at 2,800 fps = 2,958 ft/lb
180g Bullet at 2,800 fps = 3,132 ft/lb

Your 8# hammer..
swung over head: 8# at 3 fps = 1.1189 ft/lb (little over one foot pound of energy).
8# at 60 mph = 962.76 ft/lb
8# at 100 mph = 2,674 ft/lb

So your 8# hammer needs 100 mph to equal the bullet.
The bullet at 2,800 fps is going 1,909 mph

 

[Gun guru]

dlppost has it right.
1/2m X v^2 is the formula for kinetic energy.
The .30-06 in 180grain has about 3150 pound feet of energy. The 7MM mag has about 3400.
I think that an expanded bullet in which all the bullet energy is impacted into the deer is how a deer is "knocked down". A straight clean shot through the stomach of the animal lets say with a non-expanding bullet is how the deer gets away. That is why if you a good enough shot just aim for the head and it drops right there. (I am talking about close range shots)

 

[MarkB_MI]

It is momentum, not kinetic energy, that "knocks down" a target. Ask the metallic silhouette shooters: heavy bullet/slow velocity beats light/fast. A .270 Winchester projectile is neither heavy nor slow.

A few simple calculations will show that your buddy's deer was not "knocked off her feet" by the bullet's inertia. If it had been, you would have seen the same effect when you shot your deer.

Momentum is velocity times mass. (As opposed to energy, which is 1/2 mass times the velocity squared.) Conservation of momentum dictates that the combined momentum of two objects after they collide must be the same as their combined momentum before the collision.

Before you shoot a standing deer, its momentum is zero.
The bullets momentum is mass x velocity:
140 grains x 2800 ft/sec = 392,000 gr-ft/sec
(392,000 gr-ft/sec) / (7000 lbs/gr) = 56 ft-lbs/sec

After the deer is hit, if the bullet doesn't exit the deer, all momentum is transferred to the animal. So we can calculate how fast the deer was "knocked down". Let's assume a 150 lb deer:

56 ft-lbs/sec = mass x velocity
velocity = mass / momentum
velocity = (56 ft-lbs/sec) / 150 lbs = 0.4 ft/sec.

So we can see that the deer barely moved from the force of the impact.

What you observed was a classic example of inconsistent bullet performance: Your buddy hit a deer in the right spot and it went down instantly. You hit is a different spot and it ran for a quarter mile. This is typical with the lightly-jacketed bullets in factory ammo. Premium bullets like Barnes and Nosler use much heavier jackets. They will almost always penetrate completely through deer-sized game. If you switch to better bullets, you probably won't see stunning results like with your buddy's deer, but you're much less likely to have deer run after being shot.

 

[buickanddeere]

The deer was hit with less energy that what your body absorbed in recoil from the rifle. As the bullet did slow some between the rifle and deer.
Recall the equal and opposite reaction thing from high school physics class.

 

[Steve in VA]

MarkB,
Nice answer. The conversion of grains to pounds is reversed though. There are roughly 7000 gr to a pound-mass. Dividing by 7000 yields the correct numerical answer but the units are simply reversed. Nice work really.

 

[Jake 2]

Here's a gun that'll...Git'er done. Only problem, the carcus comes back already ground up ! ! !




http://www.vincelewis.net/20mm.html
Untitled URL Link

 

[Mel in SW Iowa]

Another variable that is inconsistent and hard to predict is the effect of hydraulic shock created
when bullets go through soft tissue. Nearby organs
are often ruptured by higher velocity bullets, but
if the shock doesn't immediately incapacitate the target, it may take years for effects to be apparent.

 

[Russ from MN]

We shoot Barnes Triple-shock bullets in our ammunition,308 and 243, 165gr and 85gr. They do a wonderful job on MN whitetails! These are solid copper bullets designed to open up and cut like a little broad head. every one we have shot the bullet has always gone through and left a reasonable exit wound. The hydraulic shock is incredible, the chest cavity is just full of mush when you field dress them, and there is no lead fragments in the meat to worry about.

 

[dhermesc]

Premium bullets like Barnes and Nosler use much heavier jackets. They will almost always penetrate completely through deer-sized game. If you switch to better bullets, you probably won't see stunning results like with your buddy's deer, but you're much less likely to have deer run after being shot.

=================================================

I think you missed something.

http://anarchangel.blogspot.com/2005/08/basic-ammo-questions-part-1.html

 

[old]

Way to many factors come into play on something like that. Grains of the bullet and grains of powder behind the bullet. Also things like bones and fat and all. I shot a doe yesterday and one shoot did not pass threw but the other did. When we dressed her out I found there was no need for the 2nd shoot since she was walking dead but I did not know that because she was in fact walking. By the way I use a SKS 7.62X39 about the same as a 30-30 as for ballistics

 

[jackinok]

to give actual hard core ballistic data .you would have to know ,weight of bullet,shape of bullet,speed out of your rifle and more. Theres two schools of thought on bullets. One is for bullet to mushroom to several times its original diameter and pass through making a good blood trail and things while expanding MOST of its energy,and the other is to penetrate into the vitals expand violently and expand all its energy without exiting. Both work, but the former will often give slower kils than the later. I would be curious as to what bullet you were using. Was it one of those plastic pointed ones? Thats pretty typical of them,from what i understand, but i've heard stories of them totally blowing apart on the hide at really close range, and not expanding at all at really long range. Bottom line ,matching the bullet to the range is the trick ,sounds like you have a good combination for your hunting. I'm sort of afraid of those bullets because i quite often hunt brush piles where the range is a few feet instead of yards , And i dont like a bullet that could blow up at high velocities. So im in the pass through school.

 

[Mike M]

I heard that called a Texas heart shot for some reason ?

 

[Mike M]

Old just don't go all "state patrol" on it and empty your clip in them !

 

[old]

Had one many years ao that I had to do that on. I would throw 3 at him and he would go down just to pop back up again. Did that till empty and he was down but still trying. He was one tough buck. A friend had jumped him up and the buck came into me. Once down we found it had both right legs broken off at the knees so how he could move so fast we never knew

 

[jackinok]

I did it once with a 44mag on a doe. Was loading a buck up when a little old doe he had been chasing came up out of a ditch and stood there looking at me. Yanked out my 44 and aimed for her chest but shot high because i hit her right on the end of the nose. She flipped over backwards into ditch and i thought sure she was down. I chased that stinking thing thru the brush for 2 hours putting another bullet thru her every fifty yards or so. She was literally shot to pieces and i still had to cut her throat. When i finally got her I found bullet had entered her nose went right up beside her skull and came out below her ear. Must have knocked her senseless is why she just kept getting up and laying down. I havent tried shooting one in the chest again needless to say,,I would have never believed you could shoot one anywhere in the head at fifty feet with a 44mag and it still get up until then.

 

[MarkB_MI]

DH, I'm afraid you're going to have to help me out here. That link goes to a blog with someone's opinions about defensive pistol bullets. What does that have to do with large game hunting bullets fired from a highpower rifle?

 

[Ultradog MN]

Real good replys folks.
One of these days I need to sit down and compare the force my 20 oz claw hammer puts onto the head of a 16 penny nail.
I do like the bullet to exit though. The second hole is usually larger and will leave you a good blood trail. I was lucky to find this deer. Very little external blood though she was badly damaged inside. Lost her trail after 100 yards but picked up her tracks where she crossed the dirt road.
I can't remember the last time I had a bullet that didn't exit. And to have both of us do it this year with such different results was interesting.
FWIW I just buy my cartriges off the shelf.

 

[GordoSD]

I've filled two tags so far this fall. Using a WInchester M70 in .270 WSM. one buck, 275 yards, ran 250 yards shot through the neck very close to the heart lung zone.
The other, 160 yards, ran in a circle for 10 seconds. Hit in the heart/lung zone.
Over the past 53 years and perhaps some 120 deer taken with my Weatherby .270 mag and this .270 WSM i have never lost a deer. I have had to resort to some good tracking by a well trained Brittany a few times, but that was because of darkness. I can count misses on one hand. But I won't take a shot over 350, always shoot prone or sitting with sling in place.
90 percent of the time I'm throwning 150 grain Nosler partition. Factory loads.
I have some new Weatherby 7mm Mag ammo if someone needs that. Email open

 

[Steven-Id]

I got lucky years ago and had a deer that I shot from about 75 yds. with 30-06 180 grain. I hit her in the neck from just about head on and the bullet went in and missed the shoulder bones and right up into the spine. She dropped like a rock, all 4 legs just curled up and down she went. When we field dressed her there was less than an ounce of blood outside of her body. No exit wound. When we skinned it there was very little bloodshot damage. Where the bullet never hit anything very solid it didn't expand until it hit the spine.


Steven

 

[TomH in PA]

Here's a good discussion of what happens when a bullet hits. Most of the damage happens because of the speed at which the energy is transferred, so there's just no comparison of a heavy slow moving object like a hammer to a lighter very fast moving bullet (which is also why the gun's recoil doesn't rip your shoulder off).
Bullet Damage

 

[XRogerX]

This is a very interesting video shot at 1 million frames per second of what happens when bullets hit their target. Perhaps it doesn"t answer your questions, but it is somewhat hypnotic to watch.
Bullets In Action