To be sure, these two cartridges are, while not quite on opposite ends of the spectrum, very different from one another. The 270 is a bottlenecked cartridge that uses a small-diameter, pointed bullet, which moves much faster than the stubby 44's big, blunt projectile. Bottom line, the 270 beats the 44 in the reach department, but within 100 yards the 44 comes out on top.
Even though the 44 has a TKO of 16.0 at 200 yards, its velocity has dwindled to a mere 1100 fps or so and energy is only about 650 ft-lbs, and penetration will likely be poor at such a long distance - a ridiculous distance for a 44 magnum, at which bullet performance will likely be poor. The 270's TKO at 200 yards is about 14 or so - 2 "points" lower than the 44's - but its energy ranges from 1600 to 2000 ft-lbs, and velocity is between 2200 and 2600 fps, indicating that at this range it still has plenty of "clobber power."
No Comparison?
From this comparison we can see that, given the chance, any cartridge-effectiveness formula will fall apart. So where does that leave us? Not in bad shape, really. We have decades of well-recorded big game hunting to fall back on, and when it comes to cartridges, there's nothing really new under the sun. In determining how well the latest 300 super-duper mag will work on game, we need to just compare its performance with its most similar predecessor, probably either the 300 Winchester or Weatherby Magnum. The same applies to most any untried hunting cartridge.
My Minimum
As for my own definition of a suitable deer-hunting rifle cartridge, I would call 27 a minimum caliber, and then I would only feel comfortable using heavy-for-caliber, well-constructed bullets such as the 150-grain Power Points I shoot in my 270 Savage. A TKO of 13 would probably be the least I would want, and in certain cases involving light bullets, even that is inadequate. Bullets that retain a TKO above 13 at longer range may also be inadequate killing tools, as is the case with the 44 Rem Mag at 200 yards. As is true with any cartridge-performance rule, this is a guideline that has many exceptions.
Maximum? There's no such thing, as far as shoulder-fired centerfire rifles are concerned. Remember - you can't kill game deader than dead.
- Russ Chastain
