by Terry Wieland
In the interests of keeping readers abreast of the odd, the unusual, and the unexpected, I offer my recent experience developing loads for an English rook rifle, circa 1890, chambered for the venerable .300 Rook Rifle cartridge.
In October, 2021, I wrote about this rifle, which followed me home from the Rock Island Auction. It bears the name “Joseph Harkom,” a highly respected Scottish maker, later part of John Dickson & Co. It was actually manufactured in Birmingham, probably by W&C Scott, to a design by Holland & Holland they called “The Ross,” after Capt. Horatio Ross, a noted shot.
Holland’s named its cartridge the .295 Rook, while Kynoch called it the .300, but it’s the same thing. It originally fired an 80-grain bullet at 1,100 feet per second (fps), propelled by 10 grains of black powder, and was the combination Holland’s used to win the rook-rifle category of the Field Rifle Tests in 1883. In that competition, their 20-shot group at 50 yards could be covered by a half-crown — roughly 1.25 inches in diameter. That’s very fine shooting in anyone’s world.
Kynoch continued to make ammunition into the smokeless-powder era, finally discontinuing the .300 Rook in the 1960s, so shooting it today is strictly a handloading proposition. It also demands some innovation, since load data is scarce, and any you find may involve obsolete powders like Cadet Neonite.
I found some Bertram cases at Huntington Die Specialties, and 80-grain bullets at Buffalo Arms. An early edition of Cartridges of the World suggested a load of 5.0 grains of Unique, which I backed off to 4.5. This gave a velocity of a (rather surprising) 1,436 fps with absolutely no indication of excessive pressures. A black-powder load of 12 grains of Swiss FFFg produced 1,232 fps.
The .300 Rook case is remarkably similar to the .32 H&R Magnum — ten thou skinnier but a little longer, with virtually the same capacity (15 grains of water versus 16.) Sierra gives a load of 4.5 grains of Unique in the .32 H&R with a 90-grain bullet. That being the case, I figured any load for it should work in the .300 Rook provided sufficient caution, such as starting with a mid-range charge, not jumping in at maximum.
Anyone who takes this approach does so at his own risk, naturally, but it seemed safe enough to me, and so it more or less turned out. I didn’t have every powder Sierra suggested, but I had a few. Those I tried were SR 4759, Trail Boss, Herco, and True Blue. The first two delivered disappointing velocities in the 850 fps range, but Herco was up there with Unique at 1,466, while True Blue delivered an astonishing 1,639! And, there were no significant signs of excessive pressure with any of them.
To clarify a little on the black powder, modern ones simply do not deliver the velocity of the English powders of the later 1800s. Sorry, but they don’t. Swiss is about the best I’ve found, and with the Bertram cases, it took 12 grains of Swiss FFFg to fill the case to the base of the bullet, which is what you need. Hence, a slightly heftier charge of black, and it did deliver an extra 132 fps over the original factory load (1,100 fps.)
Now for the strange part. Had I been offered a bet, I would have said Unique would deliver the best accuracy and, in fact, Unique was second best (1.75 inches for five shots at 50 yards). Herco was very close to Unique, while True Blue was the worst — about a six-inch five-shot group.
The Swiss FFFg? Five shots into a group that measured 1.3 inches, with four of them touching in a cluster .75 inches across. In other words, very close to Holland & Holland’s result at the Field trial in 1883. I didn’t have a half crown handy, but I’m sure it would have pretty much covered the group. Not only that, the group was only about two inches above point of aim, while the others were considerably higher.
Like most rifles of the era, the Harkom’s sights are regulated to shoot with one load, and are not readily adjustable to accommodate different bullet weights or velocities. Short of installing a higher (custom made) front sight, there’s not much I can do, but I’m more than willing to settle for this black-powder load, which is probably just about dead on between 75 and 100 yards.
Overall, though, the results are strange: The newer the powder, the higher the velocity, the worse the group size. Explain that one.
One reason Gray’s Shooting Editor Terry Wieland continues to be fascinated by ballistics is that you just never know.