Caliber .270, bullet diameter .277-inch, is primarily an American phenomenon based on the .270 Winchester, which was introduced in 1925. Its origin is murky; there was an experimental 6.8mm Mauser developed for China so rare that standard references show no photos. No evidence confirms that Winchester was even aware of this obscure cartridge.
Nobody knows for sure why Winchester’s Roaring Twenties engineers settled on that bullet diameter. They probably wanted something based on the .30-06 case that might shoot flatter, kick less, and be almost as versatile. There were other options; both the 6.5mm and 7mm (.264 and .284-inch) bullet diameters were popular in Europe and making inroads in the United States, but in xenophobic post-WWI America, using a “European” diameter might have been out of the question.
A Possible Explanation for the .270 Winchester?
So why .277-inch? Some time back one astute reader offered a plausible explanation. Winchester’s mild .25-35 was extremely popular. As early as 1912 Charles Newton necked the .30-06 case down to take a .257-inch bullet. In 1915, Newton teamed with Savage to design the first cartridge to break 3000 feet per second, the .250 Savage.
By 1925, the Savage 99 lever action in both .250 Savage and .300 Savage (1920) were giving Winchester a run for their money. The .270 sort of splits the difference between the .25 and .30-caliber–the .25 was questionable on game larger than deer, and the .30-caliber was effective but carried a price in recoil. Perhaps the explanation is as simple as that!
Weatherby, WSM, and SPC: Three Other .270 Cartridges
Whatever their rationale, Winchester hit it right. The .270 Winchester was a huge success, and has remained so to this day. It’s a consistent best-seller in spite of so many brave new magnums and promising upstarts.
Surprisingly, in the last 93 years, the .277-inch bullet diameter has spawned just three other cartridges, the .270 Weatherby Magnum (1945), the .270 WSM (2001), and the 6.8mm SPC (2003). The two “magnum” .270s are fast and effective, about as flat-shooting as any sporting cartridges in the world. I like both of them, but they have not encroached significantly on the .270 Winchester’s popularity.
The 6.8mm SPC was designed as a military cartridge sized for the AR15 platform, offering a more powerful option to the 5.56mm NATO cartridge. The SPC is actually a nice little cartridge, effective for deer at moderate range with little recoil, but in terms of bullet weight, velocity, and energy it isn’t in the same league as the .270 Winchester. And that’s the entire spectrum of .270-caliber cartridges, with only the .270 Winchester achieving lasting popularity.
The 7mm: A European Tradition
Now let’s turn to the 7mm, a European standard since the 1890s. The Grand-dad, the 7×57 Mauser (1892), quickly achieved (and retains) some following in the United States. It received more worldwide acclaim when renamed .275 Rigby in the British gun trade. The 7×57 remains one of my favorites. In truth, with the right loads, the 7×57 comes pretty close to .270 Winchester performance! So does the short 7mm-08 Remington (1980). There is also a long lineage of faster 7mms, including the .280 Ross (1906), the .275 H&H Magnum (1912), and the 7×64 Brenneke (1917), but none achieved popularity in the U.S.
In the 1950s, prominent gunwriters such as Les Bowman and Warren Page clamored for a fast 7mm. They already had one in the excellent 7mm Weatherby Magnum, one of Roy’s original cartridges, but for some reason this was largely ignored. The 7×61 Sharpe & Hart (1953) made some inroads, but it was Remington that became the great champion of the 7mm. Their .280 was introduced in 1957 in their Model 740 semiautomatic, initially with fairly mild loads. It wasn’t burning up the world, but in 1962 they gave 7mm fans their answer: The 7mm Remington Magnum. It took off like a rocket, for many years the world’s most popular “magnum” cartridge.
Remington wasn’t done. In 1989, they standardized Layne Simpson’s full-length belted wildcat, the 7mm Shooting Times Westerner. In 2000, they topped it with the 7mm Remington Ultra Mag, still the fastest 7mm factory cartridge.
That hasn’t been the end, though. Both Winchester and Remington introduced short, unbelted 7mms (7mm WSM and 7mm RSAUM). The most recent “fast 7mm” is the 28 Nosler. Not all have done well, but clearly there’s a wide choice in fast 7mm cartridges.
How Energy Transfer Affects “Hitting Power”
Fans of the 7mm magnums tend to think of them as magic wands, citing capabilities with heavier bullets, and the almost magical aerodynamic and penetrating properties of the 7mm bullet diameter. These folks typically ignore the .270s.
One of the most poorly understood concepts in terminal ballistics is energy transfer, which is difficult to quantify because it doesn’t always consider bullet performance. Elmer Keith believed frontal area (bullet diameter) made a big difference. So do I! Keith believed that his beloved .33s hit harder than .30-calibers. I agree with this, too. Assuming similar bullet construction, I’m certain a .30-caliber hits harder than a 7mm, .270, or anything smaller in caliber. But how much difference in diameter is needed to make a noticeable difference in “hitting power”?
.270 vs. 7mm: Is there really a difference?
The difference between the .270’s .277-inch bullet and the 7mm’s .284-inch bullet is just .007-inch, seven thousandths. Put .270 and 7mm bullets side by side, and the difference in diameter almost escapes the human eye. The current surge of interest in the 6.5mm brings up similar arguments. There is .013-inch (thirteen thousandths) difference in diameter between the 6.5mm (.264) and the .270 (.277).
I’m prepared to concede, when bullets of like weight, construction, and velocity are used, there isn’t notable difference between .270 and 6.5mm performance. However, I’m absolutely convinced the 7mm hits harder than the 6.5mm, and equally convinced that the difference between the .270 and the 7mm is just too close to call!
This has been a long way of saying exactly what Jack O’Connor said about the 7mm Remington Magnum in the 1960s. His analysis was that it wouldn’t do anything his .270 couldn’t do…and I think he was right.
7mm Cartridges Can Use Heavier Bullets
I can hear the 7mm fans howling for blood. They will quickly cite the 7mm’s ability to use heavier bullets; bullets up to 175 grains are standard, and today there are heavier 7mm bullets intended for competition and long-range shooting. Standard .277-inch bullets stop at 150 grains, and heavier choices are few. This argument is valid if you use heavier bullets.
Back when I was doing a lot of my hunting with two pet 7mm Remington Magnums I almost never used 175-grain bullets; I rated them too slow and unnecessary. However, I usually loaded up 160 or 165-grain bullets. In my mind, these offered a visible advantage over the 130-grain bullets most common in .270s. However, realistically, we have better bullets today, and my experience is that the most common 7mm bullets in actual use today are from 140 to 150 grains. These offer no discernible advantage over .277-inch bullets from 130 to 150 grains.
A Word About Accuracy
Accuracy is another issue, and it cuts two ways: first in raw accuracy, and second in bullet development. The .270 Winchester has never been considered a match-grade cartridge. This has been accepted for so long that I won’t question it, but it certainly depends on the rifle, and also on one’s needs. I’m neither a benchrest nor a long-range competitor.
As a hunter, I’ve found most .270s consistently and adequately accurate, and a few have been spectacular. However, without trying to figure out whether the chicken or the egg came first, since almost no one considers the .270s competition-grade cartridges there has been little development in either match grade or long-range bullets.
In this arena the 7mm has long since left the .270 in the dust. Until recently this was also true of the 6.5mm, but now that the 6.5s are the long-range darlings, development of both new bullets and cartridges continues apace.
The .270 as a Hunting Cartridge
Taken all together, this leaves the .270s as primarily hunting cartridges, and good ones at that! I am convinced that, as hunting cartridges, the super-fast .270 WSM and .270 Weatherby Magnum are as versatile and effective as any 7mm cartridges. I’m also convinced that the .270 Winchester is as versatile and effective a hunting cartridge as any of the 6.5mm and 7mm cartridges except for the very fastest numbers.
It’s taken me nearly a lifetime to accept this, but as I grow older I have to concede that Jack O’Connor was right about his pet .270. It is near-ideal for the full run of deer hunting, a superb choice for mountain game, and plenty adequate for game up to elk. The same can be said of the 7mms… but I’m hard pressed to believe they’re actually better. The differences are just too close to call.