April 18, 2023
Let us begin with an interesting fact. Of the myriad .30-caliber belted magnums available in the 1980s, the one determined to be the most efficient—that is, measured velocity for the amount of powder employed—was the once-revered but now largely ignored .300 Holland & Holland.
You can enlarge the cartridge case and stuff in more powder, but the law of diminishing returns kicks in and eventually you are just wasting propellant. Two things you will undoubtedly get, instead of increased velocity, are a much magnified muzzle blast and heavier recoil.
Ken Waters, for years America’s indefatigable test-shooter and oracle on all things ballistic, reported that his experience showed the velocity increase realized from two larger .300s (the .308 Norma Magnum and the .300 Winchester Magnum) amounted to only 27 to 72 fps in the former case and 37 to 79 fps in the latter. This was averaging maximum charges with various bullet weights. Hardly seems worth the effort, considering one can have that much variation, shot to shot, with identical loads.
For the record, the only meaningful improvement Waters found was with the much larger .300 Weatherby—and then only in 26-inch barrels.
Another under-appreciated and now largely forgotten magnum was Philip Sharpe’s 7x61 Sharpe & Hart. Ballistically, it fell between the .280 Remington and the 7mm Remington Magnum. Ignore any ballistic table you find for it from the 1960s, wherein the advertised velocity was 3,100 fps with a 160-grain bullet. This was achieved (if, in fact, it was achieved at all) with a 30-inch barrel. Thirty inches? You kidding me? Who would go hunting with a vaulting pole like that?
The best any investigator was able to achieve was down around 2,900 fps, and once that got out, the 7x61 was a dead duck. The advent of the 7mm Rem. Mag. in 1962 hammered the last nails into the coffin.
With newer powders, you can get 3,000 fps with a 160-grain bullet. However, leaving aside any preoccupation with sheer velocity, what we find in the 7x61 S&H is a very efficient cartridge. According to the 1969 Lyman manual (#45), the 7x61 was the most efficient 7mm cartridge tested, delivering the most bang for the buck. Combine that with the fact that it’s extraordinarily accurate in the rifle for which it was chambered, load a 140-grain bullet to an effortless 3,000 fps, and you have a great hunting rifle.
My Schultz & Larsen Model 65 DL will plant its bullets into tiny groups just like those from my Jarrett .257 Weatherby, which is guaranteed to shoot half-inch groups. On a given day at the range, the 7x61 will do better; another day, the Jarrett—and the Schultz & Larsen was a factory rifle, albeit an expensive one.
I don’t know that anyone has tested efficiency in .25-caliber rifles particularly, but the .257 Weatherby has been one of my favorite cartridges for almost 35 years, since I got my first one, a custom Safari-grade Mark V. If I had to guess, I would say it was just about the sweetest of sweet spots for any powerful .257. Of course, it requires a 26-inch barrel to deliver its ballistic performance, which turns it into something quite different than your average .25-06.
The .300 Holland & Holland, at almost 100 years old, has nothing left to prove to anyone, either on a target range (remember Ben Comfort and the 1935 Wimbledon Cup at 1,000 yards) or hunting on any continent. Waters wrote that it was his all-time favorite cartridge, not least because its shape resembled an intercontinental ballistic missile.
If I had to pick one—just one magnum—to do it all, I guess it would have to be the .300 Weatherby. But please, don’t make me do it. The thought of being restricted to a single magnum rifle is too much to bear.