VAhuntr

NoMercy448,

Very informative post. I'm curious as to how much weight you put in the TKO values? Reason I ask is I seem to remember that a slug fired from a 12 gauge shotgun and the 44 magnum(just to name a few)had higher TKO's than the 30-06/270/7mm Rem mag.

DavidD.

Damn guys! Thanks for all the awesome info, I really appriciate it and have learned a ton! I'm going with the .270 I think, I really like Weatherby so I think I'll go with a Weatherby .270 or a classic Remington 700!

Nomercy448

I weight the TKO values along side the velocity and energy numbers. It's not my ONLY consideration, but I use it to compare the relative "effectiveness" of a given round to transfer it's energy to the target (assuming bullets of similar construction).

What it comes down to is that that the TKO factor is a relative comparison for how well a bullet is able to transfer its energy (or actually, its momentum) to the target. Basically, if I compare the total energy difference between two cartridges, then factor in the TKO factor as the "relative energy transfer coefficient", I can mathematically estimate the relative energy transfer for both cartridges. The greater the energy transfer, or intuitively, the better the energy transfer rate, the wider the "cone" of the impact will be, i.e. the cone of the hydrostatic shock, and the wound channel. The lower the energy transfer rate, the more the bullet will behave like an FMJ, or an arrow. The higher the energy transfer, the bigger the wound channel, the bigger the hydrostatic shockwave, and the more bleeding.

Clear as mud, right?

So say Cartridge A has 10% more energy than Cartridge B, but B has a 30% higher TKO factor. I would expect Cartridge B to actually transfer MORE energy to the target, better than A, even though Cartridge A had more energy. Energy: Cartridge A = 1.1 x Cartridge B, A > B, TKO: Cartridge B = 1.3 x Cartridge A, now I combine these two equations to estimate relative Stopping power: Cartridge B = 1.3 x Cartridge A / 1.1, Cartridge B = 1.18 x Cartridge A, meaning Cartridge B actually has 18% better stopping power than cartridge A. Even though it has 10% less energy, it will transfer it's energy BETTER, for a greater net transfer of energy.

Here's an example: Which is better for elk? a .270 or a .308win? The off the cuff "gun guy" answer is the .308win. Why is that? Most the time, you just get the "well, you need a 30cal for elk", or "well, it's a harder hitter". Generations of experience with both cartridges proves it to be true, but why?

For 150grn bullets, the .308win and .270win are almost identical. Both should be trucking about 2900fps, KE = 2801ft.lbs., 62.1lb.ft/s momentum. HOWEVER, the .308win will have a TKO factor of 19.1, while the .270win only has a TKO of 17.2, an 11% favor for the .308win. So energy: .270 = .308, transfer: .308 = 1.11 x .270, therefore net relative transfer: .308 = 1.11 x .270. I would expect the .308 to transfer 11% more energy than the .270, even though they HAVE the same energy.

What if we hadn't considered the same bullet weight and velocity, but had used the "prime" for each, a 130grn bullet for the .270 and 165grn for .308win. The .270win will be pusing 3125fps, have 2818ft.lbs. KE, momentum of 58.0, and a TKO of 16.1. The .308win, however, will be trucking 2800fps, with a KE of 2872ft.lbs, a momentum of 66, and a TKO of 20.3. Even though the .308win will drop a little faster, and only has 2% more energy (basically the same energy), it has 14% more momentum, and 26% better TKO factor. I would expect a much better blood trail, and a much harder hit from the .308win than the .270. In this case, Energy: 308 = 1.02 x .270, Transfer: 308 = 1.26 x .270, therefore the net relative transfer should be around 28% greater for the .308win.

Ultimately, both will kill a deer, but I would expect more tissue damage from the cartridge with the higher net energy transfer, meaning I'd get better bleeding, and better hydrostatic shock, which for the hunter means, the deer isn't going to run as far, and it's going to leave a better bloodtrail (although it ALSO means it's less likely to produce an exit wound).

Again, this is just putting numbers to stuff we already know happens in the field.

To speak directly to your point about 12ga and .44mags having higher TKO values than the .270win, yes, they do. HOWEVER, when we look at the total energy, it's obvious that they aren't heavier hitters.

Lets look at the .44mag vs the .270win. A 240grn .44mag will be trucking 1450fps, KE = 1120ft.lbs., momentum = 49.7lbm.ft/s, TKO = 21.3. A 130grn .270win, again, will be running 3125fps, KE = 2818ft.lbs., momentum 58.0, and TKO = 16.1.

So, essentially, the 270win has 152% more KE, but the .44mag has 32% higher TKO. Relatively, speaking, the .44mag would transfer it's energy MUCH better than the .270win, but the .270win has a LOT more to deal with. Again, the .270 = 2.51 x the .44mag energy, the transfer of the .44mag = 1.32 x the .270 transfer, so ultimately the relative energy transfered by the .270 = 2.51 x .44mag / 1.32, or .270 = 1.90 x .44mag, showing that the .270 will transfer 90% more energy than the .44mag, even though the .44mag has a higher TKO factor.

(On a somewhat related side note, after 200-250yrds, the velocity of the .44mag has dropped low enough that the .270win will actually "catch" it on TKO factor. Which is another thing I consider. I've never shot a deer with my muzzle against their hide, so muzzle velocity/energy/TKO doesn't matter very much to me other than as a starting point for my calculations/trajectory. How it performs at the ranges I need is what is most important.)

So no, I don't ALWAYS go with the higher TKO factor, but I DO weight it equally to total energy, and trajectory, just as another compounding factor in my cartridge choice decision.

VAhuntr

Been hunting since 1978 and have seen a bunch of deer killed in that time. Some of the nastiest wounds I've seen have come from rounds such as the 243 Winchester, 270 Winchester, 25-06, and 257 Weatherby. It is really hard to argue with any of the above listed cartridges as they have been performing flawlessly for a long time.

helmsman

get the 270 and a 3-9x40 scope. set scope at 3x when hunting in thick areas. don't try to shoot through bushes, limbs, thickets at deer. this ain't a difficult decision. good hunting.

Nomercy448

No matter what the numbers say, choosing a cartridge is ultimately up to each individual shooter. Variety is the spice of life. If you're going to own ONE rifle, you need a little more versatility than a guy that owns two or more rifles, but ultimately, every cartridge has it's own "flavor".

I absolutely LOVE the .45-70 for deer. As well as the .44mag. If I have a big buck on the trailcams but haven't pinned him down, yeah, I'm going to take the .300WSM to give me some extra range, but it sure makes for a good story when you dump one with a big old pumpkin ball too.

I'd never say the .30-30 isn't a good deer cartridge (or the .270, .308, etc etc etc), but if I were faced with choosing ONE big game rifle, it would be a .300WSM or 7mm WSM Savage 12 Stainless/Laminate with Fluted heavy barrel, topped with a Bushnell 6500 4.5-30x50mm glass. There's nothing that rig couldn't do on the American continents. Yeah, it'd be a little heavy for hill country, but I'm still young enough to portage a 13lb rifle through the woods (that's what Mule's are for, right? Both the 4legged and 4 wheel varieties).

Thank goodness I'm not faced with such a nightmare!

Huntr2

.270 way better cal.

Huntr2

I read a test once, the idea of a 30/30 being a brush gun over like a .270 is not the case. In my opion any bullet-arrow or whatever hits brush its a deflected shot anyway.

Zegloff

Im not a vary avid hunter. Between work and college I dont have very much free time to hunt. But even with my little experience I love my 30-30 because of the fact of how light it is. Its great if you have to walk a while to your stand or where ever it is you hunt and then while tracking your kill. Makes it ten times easier to do this with a lighter gun.

VAhuntr

If you were using a .270 Winchester then you would not have to "track your kill", as it would likely drop within eye sight. Just picking at you a little there.

I have never found a scoped, sporter weight bolt action rifle to be any problem to tote in the woods.