Sheep Calibers

Thankfully, the Boone and Crockett Club gives us likely the only real data available to shine some light on the question at hand. For decades, the Club has tracked the calibers used to harvest North America’s record-book big game, including wild sheep rams. To be clear, the statistics included in this article do not provide the full picture of every ram ever taken with a rifle. Rather, they serve as a snapshot of which calibers have historically been most popular with those harvesting record book rams. 

This AZ desert ram was taken with a .270 Winchester by M.E. DeBruyckere

Also to be noted: not every ram taken makes B&C’s record-book standards, nor is every ram taken that would qualify entered into record by the hunter. But when it comes to rams officially measured and recorded, four rifle calibers stand taller than the rest. Together, they’ve shaped the culture of sheep hunting as much as the mountains themselves.

The data starts, fittingly, with the .270 Winchester. Introduced in 1925, the cartridge wasn’t an overnight sensation. But then came Jack O’Connor–writer, sheep hunting legend, and lifelong evangelist for the .270. Through decades of columns in Outdoor Life, O’Connor made the .270 synonymous with high-country hunting. He carried it after desert rams in Mexico, Dall’s in Alaska, and bighorns in the Rockies. The cartridge’s flat-shooting, mild-recoiling performance fits sheep hunting perfectly, and it quickly earned a place in the hearts (and gun safes) of countless hunters.

Sure, by today’s standards, the .270 might be outdated, and younger hunters may roll their eyes at their granddad’s rifle. But its record still speaks loudly: 132 book rams. Even if the .270 has been overshadowed by newer cartridges, O’Connor’s ghost still seems to smile every time a hunter shoulders one on a windswept ridge.

As the decades rolled on, magnums muscled their way into the picture. The 7mm Remington Magnum, introduced in 1962, was the cartridge that truly changed the game. Hunters immediately saw it as the best of both worlds: flat shooting like the .270, but with heavier bullets and more downrange punch. It didn’t punish shoulders like the .300-class magnums, but still hit hard enough to anchor a sheep at the far end of a canyon.

It didn’t take long for the 7mm Rem Mag to become the darling of sheep hunters. Over the years, it has accounted for 233 record-book rams, by far the most of any cartridge. Its balance of trajectory, recoil, and killing power cemented it as the king of the mountain. If you asked a sheep hunter in the late 20th century what caliber they trusted most, odds are good the answer would have started with “seven.”

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From the deserts in the south to the Canadian mountains—the top caliber for harvesting wild sheep since B&C has started tracking the data is the
7mm Remington Mag. Pictured here: Kevin Bagley (desert ram) and Jay Webster (Stone's sheep).

But not every hunter wanted balance. Some wanted sheer horsepower, and for them, the .300 Winchester Magnum was the answer. Introduced just a year after the 7mm, the .300 Win Mag quickly proved itself as the hammer that could do it all. Elk, moose, sheep—you name it, the .300 Win Mag dropped it. For sheep hunters, it offered confidence that no matter how far the shot, especially with some crosswind, the bullet would still arrive with authority.

With 185 record-book sheep to its name, the .300 Win Mag has clearly earned its reputation. Its downside, of course, is recoil. In a featherweight mountain rifle, the .300 Win Mag can be brutal on the shoulder. But plenty of hunters were willing to take the punishment for the peace of mind it delivered when a once-in-a-lifetime ram finally stepped into range.

The second-ranking caliber is the .300 Winchester Magnum, credited for these beautiful rams, taken by Paul Cooke, Clark York, and Lindsey Stroud.

And then there’s the upstart—the .300 Winchester Short Magnum. Born in 2001, it’s the youngest cartridge in the record books, yet it’s already stacked up 126 rams. The idea was simple: all the power of a .300 Win Mag in a shorter, handier case. Hunters embraced the lighter rifles and slightly softer recoil, and before long, the WSM was making its mark on the sheep world.

It doesn’t have the nostalgia of the .270, the balance of the 7mm, or the universal familiarity of the .300 Win Mag. But the fact that it’s climbed into the top four in just two decades is proof enough that it has a strong following. Like a rookie guide who surprises everyone on his first season, the .300 WSM has quickly shown it belongs in the conversation.

Rounding out the top four sheep calibers is the .300 WSM. Ronald Selby harvested his record-book bighorn in Montana with the caliber.

So what of the recent 6.5 craze? All this author can say is it hasn’t shown up in B&C records data with any authority, yet.

So, who’s “Top Gun” in sheep hunting? By the numbers, it’s the 7mm Remington Magnum. By tradition, it might be the .270 Winchester. By brute force, the .300 Win Mag. And by potential, the .300 WSM. But here’s the thing: no list, no statistic, no record book will ever end the arguments. Sheep hunters are stubborn that way. So, choose your caliber wisely. But pay even closer attention to who you’re sharing sheep camp with.

While not a top-ranked caliber, the 6.5 Creedmoor is responsible for over 40 record-book rams like Steve Johnson's Stone's sheep.

To learn more about categories, locations, dates, cartridges, and a slew of other valuable data related to the harvest of record book trophies of 38 different big game species, subscribe to Boone and Crockett’s Big Game Records Live.