Handloading the .300 Rook Rifle Cartridge

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Handloading is not supposed to be an adventure. Fascinating? Yes. Illuminating? That, too. It’s also supposed to save money, tailor loads to your needs, and keep old guns shooting when no commercial ammunition is available. What it is not supposed to be is eye-, finger-, gun-, or life-threatening.

Having emerged from 60 years of handloading with all body parts intact and no history of unintentional gun damage, I find myself—oddly enough—more fearful, not less, when it comes to crossing the line. Over the years, I’ve read enough accounts of handloaders who became, first, arrogant, then careless, and finally dead. Loaders like J. Bushnell Smith, who reportedly blew up his entire shop when some ash from his ever-present cigar dropped into the open keg of Unique (I think it was Unique) that he kept beside his loading bench for convenience.

At least, that was everyone’s conclusion, since there was little left in the way of evidence.

With that cautionary tale as a prelude, I would like to share the results of a recent venture into determining proper loads for an almost forgotten cartridge, chambered in an exquisite little rifle that I really wanted to shoot.

The rifle is a Joseph Harkom single-shot rook-and-rabbit rifle from the late 1800s. The cartridge is the once-famous .300 Rook Rifle, probably developed by Holland & Holland in the early 1880s. Originally, it used 10 grains of blackpowder and an 80-grain roundnose bullet. Later, Kynoch listed ammunition loaded with smokeless powders, so it was certainly safe to do that.

Those Kynoch powders are long-since obsolete, but there was a ray of hope in a listing in early editions of Cartridges of the World. It suggested a load of 5.0 grains of Unique with a 90-grain bullet. This load was omitted from later editions—for reasons unknown—but that fact alone indicates caution. However, Colin Greenwood, in The Classic British Rook & Rabbit Rifle, gave a load of 4.5 grains of Unique with an 80-grain bullet, so I tried that first.

One thing to keep in mind is that modern brass (available from Bertram) does not have the same inside dimensions, and hence capacity, as original brass, and this affects pressures. Altogether, there are more than enough good reasons to proceed with caution. However, I found that 10 grains of Swiss FFFg worked well with Bertram brass and some 80-grain bullets from Buffalo Arms, as did 4.5 grains of Unique.

The old small-rifle cartridges were being developed at the same time as, and some are very similar to, original revolver cartridges. None were high pressure, and load data might exist for comparable surviving revolver rounds where there is none for the rifle. The .38 Special is an example; the .32 S&W Long is another.

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Since I wanted to try some other powders, I reasoned that the .300 Rook is nearly identical to the .32 H&R Magnum. It’s a few thousandths longer but a few thousandths narrower, and water capacity is within a grain of each other (15 and 16 grains respectively). That being the case, and since all the manuals suggest a load of 4.5 grains of Unique with a 90-grain bullet in the .32 H&R Magnum, it stands to reason that any other load offered for the cartridge could be applied to the .300 Rook—always beginning with loads on the low side, of course.

With that in mind, I tried Herco and Ramshot True Blue. Both delivered velocities well above what I expected, but accuracy was poor with the former, worse with the latter. In fact, accuracy with all the smokeless powders was not great. Since the 80-grain bullets were a slightly loose (two thousandths) fit with the bore, I thought that might be the problem.

The solution? I reverted to blackpowder and found that 12 grains of Swiss FFFg fit nicely in the Bertram case to the base of the bullet. It not only upped the .300 Rook’s velocity from the old standard 1,100 fps to 1,230 fps, but also bumped the bullet diameter (as blackpowder will) to hug the bore and gave me a 1.3-inch, five-shot group at 50 yards.

In the end, I was back where I started, but the journey was educational and, most importantly, not life-threatening. And the sweet little rifle is shooting like a dream.