Recent Developments In Rifle Cartridges
January 04, 2011
It's hard to deny that the .404 Jeffery case influenced recent cartridge development.
We have seen a strong field of new rifle cartridges in the last decade. As I developed load data for them, I gathered a lot of impressions about their usefulness and performance. Please note that when I am talking velocities, I'm using pressure-barrel velocities to keep the apples with the apples. Many rifle cartridge loads published in the Speer manuals reflect sporting-rifle velocities that may be slower.
Here's how my ballistician's mind sees some of our newer standardized rifle cartridges.
The Short-Action Magnums
This group includes the Winchester Short Magnums (WSM) and Super Short Magnums (WSSM), the Remington Short Action Ultra Mags (RSAUM), and the Ruger Compact Magnums (RCM). First, I think Remington and Ruger came up with the technically better names; the term "short-action magnum" was, in my opinion, already taken decades before. It was originally used to describe magnums based on the H&H Magnum case but shortened to work in standard .30-06-length actions. Famous examples include the .300 Winchester Magnum, the 7mm Remington Magnum, and the .338 Winchester Magnum. The latest series was designed to work through the .308-length short-action rifles; that information should have been incorporated in all the names. But that's one man's opinion.
It's hard to deny the influence of the .404 Jeffery case when looking at the new Remington and Winchester cartridges. They may not match it point for point, but the overall dimensional similarities of the head and the rebated rims certainly suggest an ancestral link.
The short cases allow something that has become difficult in the conventional long magnum cases: efficient reduced loads. These are very useful for low-recoil practice or training recoil-sensitive new shooters. Although we were able to get some useful loads for the larger cases, it was no easy task. The new short-action magnums proved to be willing participants in our reduced-load development. We used Accurate Arms 5744 propellant and found a number of dandy and highly efficient loads.
The .223 WSSM is the smallest, and frankly, I did not expect much from it. However, lab results didn't lie, and we saw this little pocket rocket post some of the highest handload velocities of any U.S. standard .22-caliber rifle cartridge. It commonly edged out the .220 Swift in several bullet weights for top velocity. It should; it held a little more powder. Still, it was impressive to one who expected much less. One caution here: The standard twist for the .223 WSSM is 1:10, making some classic thin-jacketed varmint bullets prone to self-destruct on the way to the target.
Although well behaved in the lab, the .243 WSSM did not fair as well as its smaller sibling when compared to existing cartridges. It was on track with the venerable 6mm Remington and beat out the .243 Winchester by a modest margin. Both older cartridges are traditionally offered in short-action bolt rifles, so this made me wonder why a "super-short" 6mm.
There were early rumors that the .223 and .243 WSSMs were hard on barrels; however, we did not see problems in running large numbers of bullets through our pressure barrels. The calibration system for pressure barrels lets lab techs spot wear and erosion issues long before they become obvious to the unaided eye, and we didn't get any red flags during our data development.
The .25 WSSM with 87- and 100-grain bullets was nearly the same as the .25-06 Remington. The WSSM with 120-grain bullets fell between the .25-06 and the .257 Roberts +P. It made me wish for a .25 WSM on the same case as the .270 WSM for Western hunting. I think my friend Lane Pearce has already looked at this option. [You can read Lane's experiences with his .257 USM wildcat in the December 2008 issue of Shooting Times.]
The .270 WSM edged the .270 Winchester by a small margin with all bullet weights. The 7mm WSM and the 7mm RSAUM both showed a modest gain over the popular .280 Remington with bullets of 160 grains or less, and they were just under what you can expect from the 7mm Remington Magnum. There was little if any statistically valid difference between the two new 7mm cartridges with canister-powder handloads.
Winchester and Remington were also in a dead heat in .30 caliber; the .300 WSM and the .300 RSAUM were too close to call with most bullet weights of 180 grains or less. Both fell in a narrow gap between the .30-06 and the .300 Win. Mag.
The .325 Winchester is probably the most interesting to me because it's the first American 8mm since the 8mm Remington Magnum appeared in 1977. With the three weights of Speer bullets, the WSM was only about 100 fps behind the Remington, and that was achieved with significantly less propellant. When you consider that the Remington version is built on the full-length H&H case, the performance of the .325 WSM is all the more impressive.
I find anything .338 interesting, so the recent .338 RCM got my attention immediately. Unfortunately, neither the .300 nor the .338 RCM were finalized to the point we could order test barrels before I retired. I'm relying on published data primarily from my friends at Hodgdon.
The RCM case differs from the Winchester and Remington head designs in that it maintains a connection with the original H&H case. The rim is not rebated like the others, and the head is the diameter of the H&H belt but without the "step" ahead of the belt on the original case. The slight reduction in diameter doesn't seem to hamper performance; handload velocities on Hodgdon's web-based data center look about like the other new short/compact magnums.
When you write reloading manuals, you always have one question running through your head: "What need does this cartridge fill?" For the various short magnums, I see two key factors to consider when choosing them or the older, conventional cartridges sharing the same bullet diameter.
One is action choice. Using a short action can save 1/4 to 1/2 pound compared to a .30-06-length action. When you must have weight savings, the shorties get the nod by providing significant performance from a lighter platform.
The other is bullet weight. With few exceptions, loading the heaviest bullet in a short case restricted propellant capacity, and we lost a lot of velocity. We tested the big Speer 200-grain Hot-Cor spitzer in the .300 WSM and found the velocities were little better than could be achieved from a comfortable .30-06 handload. However, bullet sales numbers show the mid-weight bullets in each diameter as the most popular, so this consideration is only for those who routinely load the heaviest bullets. If you prefer 175-grain 7mm or 200+-grain .30-caliber bull
ets, stick with the conventional longer cases.
Beyond these, the choice comes down to less tangible options, like your riflemaker preference or options. The best thing about this series is that it finishes the job of separating the word "Magnum" from "belted case." I have a pet peeve about belted cases that I'll save for later, but going "beltless" is, for me--a significant advance.
In Between--The .338-06 A-Square And .338 Federal
I've always liked the .338-caliber cartridges because they truly add larger-game potential. If you have a good .30-06 and want to hunt dangerous bear, going to one of the .300 Magnums with the same bullet loaded a few hundred fps faster is, to me, a much less appealing option than moving up to the .338-inch cartridges (or larger) with heavier and often tougher bullets. Some people say I preach overkill on this, but I am very fond of my wife's husband!
The .338 Winchester Magnum is a proven performer that introduced that diameter to modern American shooters and made component bullets available in that size. The .338-06 started as a wildcat to reproduce the .333 OKH popularized by Elmer Keith's writing but with readily available bullets. Art Alphin of A-Square standardized the cartridge around 1998. With 250-grain-bullet handloads, the .338-06 edges out the .35 Whelen, and 200-grain bullets clock within 200 fps of the mighty .338 Winchester. Again, no belt--this one is a necked-up .30-06.
I would feel quite comfortable carrying a .338-06 afield anywhere in North America. It might be a tad light for dangerous bruins, but I'd rather have this than just about anything starting with ".30."
If the .338-06 has a little brother, it's the .338 Federal. Like the .338-06, it started as a wildcat called the .308-08, which is based on the .308 Winchester case. I admit to liking "cute" cartridges, and this one fits the description. However, field-testing showed this little package is more than just a pretty face.
Federal and Speer engineers tested this cartridge on elk, not deer. Skeptical guides were very impressed with the way this cartridge brought down big bulls. It provides the deep-woods performance of classic "brush guns" in chamberings like the .348 Winchester and the .35 Remington but with a flatter trajectory, should a long shot develop.
The author came up with his idea of the perfect .30-caliber Magnum (left) well before the short-action magnums appeared. The .30-06 (right) is shown for comparison.
A Big Case I Like
Although I came away with the impression that the 7mm and .300 Remington Ultra Mags were cartridges waiting for a new generation of consumer propellants, the .338 Ultra Mag showed it was ready to run today. With 250-grain bullets, it beat the .338 Win. Mag. by nearly 300 fps without showing any bad habits. Obviously, any "mega-case" is happiest with the heavier bullets, but the .338 RUM was well behaved across the gamut of bullet weights we tested.
I suspect the .375 RUM will also be an outstanding big-game cartridge. Sadly, we ran out of lab time before we got to this one, even though we originally planned to include it. When the boss sets a date for taking a manual to press, one must salute and obey.
The .458 Lott
Okay, it's another big one. My impressions are entirely based on our lab work; recent shoulder surgery has limited my rifle shooting to low-recoil cartridges for the near future. The .458 Lott was a wildcat effort to upgrade the .458 Winchester to meet the magic 2,400 fps desired by many African hunters. Later, it became a standard cartridge. Factory 500-grain ammo and our handloads failed to make that number but still offered a 10-percent gain over the Winchester version.
What was truly impressive was the Speer 350-grain Hot-Cor, a tough flatpoint designed for North American hunting. Normally, a lighter bullet in a case this long could show some troublesome ballistic behavior, but we saw nothing but excellent ballistics indicators. Top loads exceeded 2,700 fps and more than 5,700 ft-lbs. That's a lot of "ouch" for dangerous North American critters.
Did They Miss One?
In 1999, the U.S. industry had an unbelted, large-base case in the Remington Ultra Mags. My first thought was "too big" for typical .30-caliber bullet weights, and the short-action magnums were still a couple of years out. I thought the better .30-caliber approach was to use the extra diameter but make both the case and the loaded round the same as the .30-06. From the handloader's standpoint, this would take better advantage of available canister propellants and still have enough capacity to handle bullets up to 220 grains.
I went as far as drawing this one up in CAD and modeling it with Quick-Load software, starting with .300 RUM head dimensions. I have a reloader's preference for long case necks, so the neck length was close to that of the .30-06. I gave it a single-sided, radiused shoulder because that's my preference. Capacity and overall performance were running with the .300 Weatherby.
Like many dreams, that one did not come true. However, one of the new standard cartridges comes close to my vision of an unbelted '06-length case--the .375 Ruger. I even like the bullet diameter.
There are certainly other recent cartridges that are deserving of praise. Just because your favorite isn't listed here doesn't mean it's not worthy. The ones I discussed are those that made the strongest impression on the ballistician in me.
Next time, I'll look back at some of the great old rifle cartridges that have always appealed to me, and as usual, I reserve the right to be prejudiced in my choices!