Originally Posted By: WebopperI think it would be awesome if bullet manufacturers would post terminal ballistics for their loads at various velocities. Don't know how you would measure that though, as that's not simple math like muzzle energy is.
I agree. The closest I've seen is the range of effective impact velocities that is published in the Hornady manual. It begins on page 91 in my 7th edition.
I'm enjoying this thread and learning a few things. I'm about to go deer hunting for the first time at the age of 67 (better late than never!). I have a 10" twist .243 sporter that I rebarreled for varmint hunting (the factory barrel looked like an annular file inside). I also have an "03 Springfield .30-06 but my tri-focal equipped eyes can't see the iron sights. Where I'll be hunting the ranges are pretty much under 200 yards but there is one location where the shot could be as much as 300 yards. So I spent some time trying to satisfy myself that the .243Win sporter was adequate to take PA whitetails (relatively small deer) out to 300 yards. I looked at energy (I'm a retired engineer, how could I not look at energy!), I read books, scoured hunting forums, and finally came to the conclusion that the .243 will do the job with the right bullet and reasonable shot placement. I'm a varmint hunter - used to shooting at and making one shot kills on critters with rather small vital zones at ranges out to 300 yards with this same rifle, so I feel good about making the shot.
It's a 10" twist and bullets heavier than 95g are questionable (and don't group well), so I bought a box of 95g Nosler BT because it looks like a bullet that will deform and expand at the expected 300 yard terminal velocity. I didn't check it by shooting it into wet phone books at 300 yards, but I didn't think of that till just this moment so I may do it - there is still plenty of time. I came up with a load that shoots them into 3 shot group after 3 shot group (it's a Model 10 with a heavy sporter barrel) so I don't use 5 shot groups) that looks like this (rifle is zeroed for the 55g Nosler BT):
at a MV of 2985 fps averaged over 12 rounds. At 300 yards it is still going about 2300 fps and has about 1100 foot pounds of kinetic energy.
I looked in the Nosler catalog and wasn't able to find any data on the usable MV range for this bullet. It is a Ballistic Tip big game bullet. The Hornady catalog has some data on velocity ranges for their bullets. The Hornady 95 grain SST I looks most like the 95g BT and has a velocity range of 2000 to 3400 fps. The heavier soft point bullets all have a minimum velocity of 2500 fps. The Nosler is a BT bullet, I picked it because I wanted good expansion.
Kinetic energy is used by folks because it represents the potential for the bullet to do "work" when it impacts the animal. The work is penetrating muscle and bone, expanding the bullet, displacing, tearing, and smashing tissue, and generally causing lethal damage to the animal. There is a lot of discussion of energy by folks on both sides of the argument who speak and write with great passion about it. I think the passion is misplaced. Kinetic energy is only one of several parameters that should be evaluated in deciding on the lethality of a bullet. Bullet construction is important - but also only one of several parameters.
I went looking for criteria by which I could decide if my bullet choice was OK. Frankly, I couldn't find any set of criteria that I would say were rationally derrived from fundamental physical principles. This isn't unusual in engineering either, especially in aerospace where I worked for 35 years frequently trying to do what nobody had done before.
I looked at the Taylor Knock Out formulla, my bullet calculates at 9.8. So what? I couldn't find a reference that said if that was enough or not. More importantly I had no idea how the formulla was developed. There is no discussion of derrivation from fundamental physical principles. Keeping in mind that grains divided by 7000 is pounds, the units of the Taylor Knock Out "number" are pounds x ft/sec x inches. That makes no sense to me. I think the derrivation of the formulla was at best a WAG. (Wild A** Guess)
I found a criteria that said it had to have over 1,000 ft-lbs of energy and be going faster than 2000 fps. It does that but I have no idea of how that criteria was developed either. It may also be a WAG, or it may be the results of some unpublished statistics taken from actual hunting data. I have no clue where it came from. I wonder if anybody does.
I happen to have some SW called "RSI" which I think stands for Risto Shooting Lab. It was written by Jim Risto. I've talked to Jim by phone a few times but never asked him what the basis is for the "game" tables in his SW. That said, in it he has a place one can type in the MV of the bullet at impact, the bullet weight and whether or not it is a varmint type of bullet, and get back a list of the animals and weights it is suitable for. In this case it says the 95g NBT, at what I calculate will be the 300 yard terminal conditions, is good for game from 69 to 172 pounds. If one goes by average game weight, that would include the PA white tail deer. But with out knowing the basis behind the tables I am not quite sure what to do with that data.
Then I ran into several folks who had hunted deer with a .243. Two of them, who I have confidence in and respect for, had used the 95g BT to kill over a dozen deer each and hadn't lost any, though they had experienced deer running 20 or 30 yards before collapsing. They mostly took broadside shots, like I'm most likely to get, and the deer droped where they were hit or within a couple of steps. That jibes with my understanding of the performance of the 95g BT which I'd expect to expand better than a conventional soft point at 300 yard .243 muzzle velocities.
I decided based on their experience that I would go ahead and hunt deer with the rifle this year, and if I enjoy the hunting (I probably will, I sure enjoy sitting in on the edge of a farmer's field looking for ground hogs - some times I see one, some times I don't, but it's all hunting) I'll upgrade to a 7mm-08 or .300 Savage in a heavy sporter barreled rifle (8.5 lbs with scope would moderate the recoil a bit) next year. That choice being based on not having ever heard anybody say either one of them wasn't an adequate Whitetail/Mule Deer cartridge.
In the end, energy, muzzle velocity, and all the rest, "except" shot placement, don't matter as much as "what works". Nothing works without good shot placement.
That's my story and I'm sticking to it.
Fitch
PS: For those who think kinetic energy is just a number and can't be measured, that is incorrect. It is a real physical property of moving masses and can be measured in a number of ways. Multiplying half the bullet mass by the square of the measured velocity is one, a ballistic pendulum is another. The bullet spends kinetic energy to over come atmospheric drag enroute to the target. With out kinetic energy to spend overcoming drag a bullet wouldn't even get to the target. The drag increases significantly and changes character when the bullet enters the target and the bullet spends energy crunching through bone, plowing through flesh, expanding, opening up a wound channel, destroying the integrity of the circulatory system, and slashing the meat into jelly. That damage results in loss of vital functions in the animal and is ultimately what kills the animal. No energy, no damage. Period. So don't disparage kinetic energy, it is a useful property for your bullet to have when it is about to enter the animal. Generally speaking more is better, within limits, but it isn't the "only" thing that matters. If the bullet design can't effectively apply it to the destruction of the critter's vital bodily functions, it does no good and the bullet continues out the other side not having done as much damage as it might have.
In the case of the .243 at 300 yards, energy is limited, but based on the record of hunting success, it is "enough" if the shot places the bullet in a vital area "and" the bullet design is such that it can apply that energy efficiently to tissue destruction at the impact velocity.
The bottom line is that kinetic energy is a necessary but not sufficient condition. Ya gotta have it, but it isn't enough all by itself.
frw
