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Short But Sweet

by Wayne van Zwoll   |  January 4th, 2011 0

The new Ruger Compact Magnums make their case as the best of the bunch.

A new horse is a good investment when the old one can no longer run. But rifle cartridges don’t go lame. They get no less useful with age, which is why the .30-30 and .30-06 are still all you need to know about .30-bores.


But centenarian cartridges get musty in our minds. So we concoct newer, more potent rounds until we reach the limits of recoil tolerance and action length. Then we reconfigure cases to fill the diminishing gaps in the lineup. As recently as the World War II, big game cartridges stateside could be counted on your fingers. From the .25-35 Winchester to the .375 Holland & Holland, they included traditional deer rounds (the .30-30 Winchester and .35 Remington), flat-shooting .25s for the prairie (the .250 Savage and .257 Roberts), all-around .30s (the .300 Savage and .30-06) and long-legged specialists for the Mountain West (the .270 Winchester and .300 H&H).

The field has since become quite crowded, capped by the eruption of short magnums. Hunters hardly need another cartridge, let alone a new short magnum, but Hornady has just announced two: the .300 and .338 Ruger Compact Magnums. At first blush, they seem redundant–thinly veiled copies of the short .300s from Winchester and Remington, and the .325 WSM. But dig deeper and you’ll find meaningful differences.

“We set out to give hunters magnum performance from short rifle actions,” explains Hornady’s Mitch Mittelstaedt, who headed the project. Nothing new there. “Our second goal was to get that muscle from 20-inch barrels.” Now that’s new.

Even short, efficient magnums typically warrant 24-inch barrels. Velocities drop off noticeably as you chop tubes below 22 inches because the substantial charges of slow powders that push heavy bullets fast need barrel time to burn. Dave Emary, the ballistics wizard who developed Hornady’s LeverEvolution rounds, says: “We’ve used proprietary means to alter propellants in the Ruger Compact Magnums, tightening their pressure curves. The .300 RCM performs about like the .300 WSM in standard 24-inch barrels, but it beats the WSM in 20-inch tubes.”

There are other dimensional differences, too. Inspired by the 2.580-inch .375 Ruger case, the .300 and .338 RCMs share its .532 head and base diameter. In contrast, the WSM series has a .535 head (which still works on the .532 bolt face standard for belted magnums). But the WSM case is rebated; body diameter starts at .555.


The .300 RCM has a .532 head and base diameter, which will allow an extra round in the magazine over short mags such as the WSM, and its slim profile should make for smooth feeding.

“WSM magazines feed RCM cartridges just fine,” says Mittelstaedt. “With a reconfigured follower, though, the smaller RCM body diameter lets us stuff four rounds in magazines designed for three WSMs.”

The relatively slender profile also helps RCMs feed smoothly. The shoulder angle is 30 degrees.

As for length, the new Hornady .300 and .338 rounds measure 2.100 and 2.015, respectively, base to mouth. They’re both loaded to an overall length of 2.840, same as the WSM line.

Says Mittelstaedt: “We kept the .338 hull shorter (.308 Winchester length) to accommodate the current crop of cannelured bullets, most of which were designed for the .338 Winchester Magnum.” He points out that necks on both RCM rounds are “about .300 inch long. Base-to-shoulder measure on the .338 is thus a tad shorter than on the .300. Case capacities run 68 and 72 grains of water to the mouth. That is, the .338 RCM holds about as much powder as a .338-06.”


The .300 (left) and .338 Ruger Compact Magnums have subtle differences over other short mags that may give them an advantage.

Capacity of the .300 RCM falls halfway between that of the .30-06 (67 grains in Remington brass) and .300 WSM (79 grains in Winchester cases).

Hornady did its initial testing with Ruger bolt rifles. “We ordered 77 Mark IIs for this project and barreled them here,” Emary explains. He acknowledges that Hornady and Ruger have worked closely on other projects and that Ruger is likely to offer factory rifles in RCM chamberings, but he won’t speak for the gun manufacturer.

“Our goal was to develop the cartridge–and that’s all we can talk about,” Emary says.”

By the time this goes to press, I expect Hornady’s lab will have final load specs for both new rounds. And Ruger may have something to say about the prospect of rifles chambered for these new cartridges as well.

My first day afield with the .300 RCM I shot Hornady’s test rifle. It wore a 24-inch barrel. The rifle fed smoothly and recoiled civilly–about like a .30-06. Quickly I ran through a very limited supply of ammunition. My best groups prone measured an inch and a half. A colleague snared Hornady’s .338 RCM rifle and managed to empty all the ammunition before I could get my hands on it.

A few days later, after my friends at Grand Island had sawn the barrels on these two Rugers to 20 inches, I hied off to a deserted range with chronograph guru Ken Oehler. While Ken set up one of his fine instruments with triple sky screens, I tacked targets. From a Lead Sled rest, three shots from the .300 RCM printed a one-inch group. The 180-grain SSTs clocked 2,804 to 2,820 fps. A second series delivered slightly higher and remarkably consistent speeds: 2,845, 2,846 and 2,847 fps.


The author’s last group of .338 RCM 225-grain SSTs averaged 2,698 fps out of a 20-inch barrel—essentially what a .30-06 produces with 180-grain factory ammo out of 24-inch test barrels.

The .338 RCM hurled five 225-grain SSTs into a group spanning 11⁄4 inches. Velocities ranged from 2,663 to 2,696 fps, with a mean of 2,678. A follow-up string of three shots yielded an average of 2,698–essentially what a .30-06 gives you with 180-grain factory a
mmo at claimed velocity (most ’06 fodder does not reach it in ordinary barrels) and roughly what you’d get from 200-grain bullets in a .338-06.

Surprised as much by the lack of muzzle blast as by the fine accuracy and husky chronograph readings, I had to re-think my views on muscle cartridges.

Before now, my favorite short magnum has been Remington’s .300 Short-Action Ultra Mag. Efficient, powerful and squat enough to feed through a Model Seven, it is civil in recoil and carries elk-killing punch as far as I’ll ever shoot an elk. While the .300 RCM doesn’t quite squeeze into a Model Seven action, it’s a ballistic match in short barrels. The .338 RCM has no counterpart in short magnum stables. It’s essentially a high-octane version of the excellent .338 Federal–closer, perhaps, to the .325 WSM.

Do the Ruger Compact Magnums merit a place in our crowded field of big game cartridges? In my opinion, they do. With .532 heads and 2.840 loaded lengths, they’ll work in any mechanism that handles Winchester Short Magnums. Because they’re slimmer, they’ll give you an additional round in the magazine (or, if rifle makers would heed my whining, less bulk in the belly with a three-round box).

Because RCMs are loaded to deliver high performance in short barrels, you can carry a lighter, handier, faster rifle without compromising bullet speed or energy.


The RCMs are designed to shine in short barrels that many hunters like to tote in the field. A rifle chambered to these rounds and fitted with a 20-inch barrel will make a handy powerhouse.

The notion of high velocities from short cases is hardly new. It dates not to the Winchester Short Magnums of the 1990s but to the .250/3000 developed for Savage by Charles Newton in 1912.

You might say the .308 Winchester and its offspring carried the idea a ballistic step farther. The belted magnums of the 1950s and early 1960s were for a time called short magnums because they bottled the hubris of the .300 Holland & Holland in cases configured for .30-06-length actions.

But Hornady’s new short-magnum cartridges are the first to add short barrels to a list of reasons to buy another rifle. Ruger Compact Magnums are tailored to the compact rifles most hunters like to carry. They’re comfortable to shoot and as accurate as I had hoped.

“Short barrels are stiff barrels,” Emary reminds me. “We often get the tightest groups from rifles with short tubes.”

Easier to maneuver in brush and on the steeps, 20-inch barrels also reduce overall rifle weight and lend themselves to full-length stocks. What’s not to like about cartridges that accelerate in short barrels to velocities traditionally possible only in long ones?

The success of these Ruger Compact Magnums at market will no doubt influence the development of others. “We’ve already considered additional designs,” Mittelstaedt hints.

What about rifles? Is Ruger secretly building up a supply of 77s chambered to the .300 and .388 RCMs? “We have nothing to do with rifle production,” Emary says with a smile.


The .338 RCM case is shorter than its smaller brother’s so it can use the cannelured bullets popular for the .338 Winchester Magnum.

I suspect by the time you read this, Ruger will have tipped its hand–and my request for a carbine-barreled .338 RCM will be working its way to the production line.

Will the new cartridges succeed? The Winchester Short Magnum line of cartridges has a big following among hunters. The .270 and .300, I’m told, have been particularly well received. According to Winchester reports, even the .325 WSM has exceeded initial sales targets.

Remington’s Short-Action Ultra Mags, by some measures superior, have fared less well–mainly, I believe, because Remington chose to promote full-length Ultra Mags for a year while Winchester launched its WSMs. Starting second doesn’t always mean you’ll finish second, but in this case Winchester never gave up its advantage.

While these short magnums have fine records afield, the Ruger Compact Magnums present a formidable challenge. How will the hunting public rank the superior short-barrel performance of the RCMs against slightly higher velocities from WSMs in standard barrels? That’s for you to decide.

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