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 ammo 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).