January 04, 2011
By Craig Boddington
The real difference with today's new magnum cartridges lies not in the rounds themselves but in the rifle/cartridge combos they make possible.
By Craig Boddington
This Alaskan brown bear fell to the .325 WSM, one of the new batch of short magnums.
The past few years have seen an astonishing array of new "magnum" cartridges come down the pike. Just to name a few, these have included Remington Ultra Mags and Short-Action Ultra Mags, Winchester Short Magnums and Super Short Magnums, Hornady's Ruger Compact Magnums and Federal's .370 Sako Magnum. And then there are new high-performance cartridges that are not called "magnums" but still provide the kind of performance we expect to get from a "magnum" such as the .308 Marlin Express and .338 Marlin Express rounds and the .375 Ruger and .416 Ruger cartridges.
With all of these new cartridges on the street, should we get rid of our tried-and-true favorites such as the 7mm Remington Magnum, the .300 H&H, the .338 Winchester Magnum or the .375 H&H? Maybe, maybe not. Before you consider such a move, however, you need to try to understand the new magnums. In short, what do these new magnums do that the old ones don't?
American riflemen have long been crazy about velocity and accuracy, but if you are considering switching to the new magnums because you think you can get more speed, forget it.
The first magnum craze of the late 1950s and 1960s was primarily about velocity, but even then the magnum cartridges from Winchester and Remington didn't do anything new because the practical limit of sporting rifle velocity had been explored by wildcatters back in the 1930s and implemented by Roy Weatherby in the 1940s. Weatherby's cartridges were good (and fast), and he was very good at marketing. It was almost certainly the growing popularity of Roy Weatherby's proprietary magnums that led to the glut of belted magnum cartridges back when I was a kid.
None of the new magnums, not a single one, reaches velocity levels that have not been reached before. Nor can they. Nitrocellulose powders still exit the bore at a bit over 5,000 fps, but bullets cannot reach this velocity because of friction within the bore.
Seventy-five years ago the .220 Swift broke the 4,000 fps barrier. That velocity has been equaled by a few varmint cartridges and by some wildcat and proprietary rounds--such as selected light-bullet loads in some of John Lazzeroni's cartridges. But considering pressure, barrel wear, recoil and sensible hunting bullet weights, 3,000 fps is still fast, and few hunting cartridges approach, let alone exceed, 3,500 fps. Trust me, nobody wants or needs a big bore at that velocity.
What about accuracy? Well, it is true that a short, fat case is conducive to accuracy because the primer's ability to ignite a larger percentage of the powder charge immediately creates an accuracy-enhancing burn curve. The same efficient burning also produces somewhat more energy per grain of powder burned, which is why cartridges such as the .300 RSAUM, .300 WSM and .300 RCM essentially equal the .300 Winchester Magnum but are able to equal it in much shorter cases loaded with considerably less powder.
Also, almost all of the new magnums are rimless and unbelted, meaning that they headspace on the shoulder, not on a belt. This tends to create more precise headspacing, which is also conducive to better accuracy.
The fallacy here is that, while the short (or long), fat, unbelted cartridges are conducive to accuracy, cartridge design is not the most important thing. Quality of barrel, mating of barrel to action, bedding and quality and consistency of ammunition are all more important factors in raw accuracy than cartridge design.
While the new short magnums are more inherently accurate because of their design, barrel quality, bedding and other factors still govern how accurate a rifle will be. The advantage of many of the new magnums is their capability to be chambered into shorter actions and therefore lighter, handier rifles — the resulting rifle/cartridge package being the selling point.
Experienced riflemen know that the short, fat .308 Winchester is a "more accurate" cartridge than the .30-06. Take 10 .308 rifles and 10 identical .30-06 rifles, and the .308s will probably win in average group size. But the other factors are important enough that one or two of those .30-06s in the test group may be more accurate than any of the .308s.
So if you're picking a factory rifle off the shelf, to some extent it's a matter of luck. The rifle you pick will almost certainly produce adequate accuracy for your needs. If you're really lucky you might pick a tack-driver. If you're unlucky to same degree, you might pick a lemon. This applies to all new cartridges as well as all old cartridges--and to all factory rifles.
If you're having a custom rifle made, you can insist on a true match-grade barrel. If you do this, then you will probably get extreme accuracy no matter what cartridge you have the rifle chambered to.
So if the new magnums aren't delivering significantly more velocity or accuracy, then what's the point? My opinion is that most of the new cartridges are really about packaging, and I don't mean marketing hype or fancy boxes. For example, short, fat .30 caliber magnums mentioned previously essentially equal the .300 Winchester Magnum but can provide this level of performance in a short (.308-length) bolt action.
The .338 RCM comes very close to the .338 Winchester Magnum--again, in a short action. The .375 Ruger exceeds the .375 H&H but doesn't come close to the .375 Weatherby Magnum. However, that power can be housed in a .30-06-length action.
This means that the shorter magnums can be housed in handier, lighter rifles. Handier is good. As for weight, whether that's an advantage depends on your recoil tolerance because lighter rifles do kick more. This is somewhat mitigated by the fact that, since the more efficient new cartridges do what they do with less powder, they do produce less recoil.
Skeptical? Well, recoil energy is based on velocity and projectile weight and affected by gun weight. Note I said projectile weight. This includes both the bullet weight and the weight of the powder charge, which together are called the "ejecta."
If you burn less powder, which the short, fat cartridges surely do, you produce a bit less recoil. But gun weight is far more important than a few grains less powder, so
if you shave weight you will quickly eat up the benefit and increase recoil.
I've never been a big champion of shorter actions, largely because, historically, there are so few left-hand short actions. But in recent years I have to say that I have come to like carrying a more compact package.
I have tried most of the new short magnums, and all do what their makers say they will do. I do not love them all equally, but some have become real pets. I love the .270 WSM, and I'm coming to love the .375 Ruger. I'm not a big guy, and the shorter action between my hands gives a nice feel.
There are other benefits. Shorter actions, by their nature, are more rigid, and thus also conducive to better accuracy. Also, because of the burning efficiency, most of the shorter, fatter cartridges are able to produce more or less full velocity from shorter barrels.
Again, I've never been a big fan of short barrels, but if you can get the same performance from a 21- or 22-inch tube that used to require a 24- or even 26-inch barrel, this is a clear advantage.
The .338 Ruger Compact Magnum (l.) and .375 Ruger are typical of the new magnums in that they deliver similar velocities to their long-action counterparts but in shorter actions and, in the case of the RCMs, much shorter barrels. The .370 Sako is basically a .30-06 on steroids, with the ability to launch a 286-grain bullet above 2,500 fps. The Barnes TSX (l.) and Super Solids were recovered from a Cape buffalo.
Of course, not all the new magnums are short, fat and rimless. The Remington Ultra Mags (7mm, .300, .338, .375) are full-length unbelted magnums that require a .375-length action. They are fatter than the belted magnums they emulate and therefore do have ignition and burning efficiency. They are unbelted, which saves magazine capacity space as well as allowing more precise headspacing. Each can appropriately be compared to an existing belted magnum (7mm STW, .300 Weatherby Magnum, .340 Weatherby Magnum, .375 Weatherby Magnum).
However, the Ultra Mags do have more powder capacity than any belted magnum counterpart (not counting the huge-cased .30-.378, .338-.378 and .378 Weatherby Magnums). So, at least theoretically, they can produce more velocity. So if you want speed, the Ultra Mags may be for you, but don't expect exponential gains. Velocity gains are at best incremental and depend somewhat on who is doing the loading.
I will concede that the Ultra Mags and John Lazzeroni's family of long, unbelted proprietary magnums aren't about packaging at all. They are about performance, and when loaded properly they're the fastest in their class.
By contrast, the Hornady-designed .308 Marlin Express and .338 Marlin Express rounds are about packaging. Both are short, fat, rimmed cartridges that provide unprecedented downrange performance from the all-American lever gun.
In any other action the cartridges wouldn't be impressive at all, but in their package--a tubular-magazine Marlin--they're hell on wheels. In fact, the new .338 Marlin Express is the first true, general purpose elk cartridge chambered in such a rifle. (Editor's note: See Wayne van Zwoll's article elsewhere in this issue).
There is one downside to packaging. It is not always easy to make the short, fat cartridges feed as well as those same actions fed with the longer, slimmer cartridges those actions were designed for. This is not a universal problem, but I have had far more feeding issues with short magnums than with all other cartridges put together.
So are you ready to trade Old Betsy? Maybe, but make sure you're making a wise choice. Velocity gains are minimal, and accuracy gains are elusive. And there are issues with any new cartridge.
One is availability. Not all of the new magnums have become popular, so the rifle you want may not be so chambered. For darn sure your local mom-and-pop gun shop cannot possibly stock all of the new cartridges. It will be many years, if ever, before any of the new magnums are as available as, say, the 7mm Remington Magnum, .300 Winchester Magnum or .375 H&H.
Being an astute rifleman, you may instantly answer, "No problem; I'll load my own." With whose data? An obvious advantage to any cartridge that has been popular for several generations is a rich body of loading data.
Information is scarce on new cartridges, and in some cases handloading may be a bit problematic. For instance, the 7mm Ultra Mag is fast and, for its performance, amazingly mild in recoil. But it is extremely overbore capacity, and there are few propellants that bring it to full performance with safe pressures.
In other cases, well, you simply can't do it. Federal's new .370 Sako Magnum is, essentially, the .30-06 case necked up to take a .366 (9.3mm) bullet, with a slightly longer case and a short neck. Federal used its High Energy propellant technology to get a 286-grain bullet above 2,500 fps, which is a .30-06 case on steroids. Handloaders may come reasonably close but will not equal this velocity with commercially available powders.
With exceptions such as the Remington Ultra Mags, the new class of magnums doesn't offer any significant gains in velocity over their counterparts.
Similarly, the Hornady-designed Ruger Compact Magnums and the .375 and .416 Ruger rounds--and the Marlin Express cartridges--are based on similar propellant technology. Handloaders will come close but cannot equal the performance of factory ammo.
So if you live in an area where sources of supply are limited, you may want to stick with tried-and-true (and popular) cartridges. Or make sure you plan ahead.
I have not embraced all of the new magnums. Come to think of it, I haven't embraced all the old magnums, either. There are just too darned many. And, of course, our long-established preferences still come into play.
Although I've used the 7mm Remington Magnum extensively, I'm not a huge fan of the fast 7mms and therefore have not embraced any of the new 7mm magnums.
Come to think of it, I haven't embraced any of the new production .30 caliber magnums, either. Again, I've used them all and they do what they're supposed to do, but I have rifles I trust in .300 Winchester, .300 Weatherby, .300 H&H and both short and long Lazzeroni magnums.
On the other hand, I have a long-loved .270 Winchester, but I now have two .270 WSMs. Left to my own devices
, my choice for a tough sheep hunt would be my short, light .270 WSM.
I'm a .338 Winchester Magnum fan, but I'm enthralled by the .338 RCM--same performance in a shorter, handier package. And I've already told you how I feel about the .375 Ruger.
So while the new magnums cannot offer more velocity and may not offer more accuracy, it really does come down to packaging. If the packaging of the new magnums appeals to you, then rest assured they do everything they are supposed to do.