Wildcat .22 Caliber Centerfire Cartridges: Obscure and a Blur

If you’re familiar with the golden age of cartridge developments, it doesn’t take long to notice that for, the most part, the .22 caliber was an important cartridge of choice. Good rifles were starting to appear, there was an upsurge in varmint hunting, and on top of all this, powders and bullets were making great headway.

Defining the pace for all this, men like Harvey Donaldson, A.E. Mashburn, Lysle Kilbourn and Roy Weatherby set the tone for small game cartridges here in the United States. They started the trend for some of the very best .22 centerfire cartridges we have today, many of which have been formally commercialized by Remington, Winchester and others.

While most present-day small game cartridges are readily available in off-the-shelf rifles, for those willing to spend a modest amount of cash to rechamber or rebarrel a rifle for a touch of nostalgia and the pleasure of shooting a vintage cartridge, these four are a great place to start.

Most can be fire-formed right in the chamber, neck sized and then reloaded. Others need a bit more work, although in a few cases you can find sources of commercial brass along with dies.

.218 Mashburn Bee

The .218 Mashburn Bee is nothing more than an improved .218 Bee, so this is an easy one to work with. In years past, it grew from the Gibson Improved, then the Ackley Improved, finally to emerge as A.E. Mashburn’s version in 1941. The Bee’s parent case is the .32-20 Win., with a rim diameter of 0.408 inch. The Mashburn version features a shoulder angle of 17 degrees—two degrees sharper than the original Bee. Case overall length is 1.345 inches, the same as the standard Bee.

To create cases for the .218 Mashburn Bee, simply take factory-loaded .218 Bee ammunition, place it into a .218 Mashburn Bee chamber and fire-form it. This will move the shoulder forward quite a bit, but in forming more than 200 cases, I’ve had few that split at the neck or case mouth. RCBS formerly offered die set No. 56030 as part of its G group, but no longer does. However, Graf & Sons currently sells custom Redding dies for the cartridge.

The difficult part with the .218 Mashburn is finding loads. Older reference books from Charles Landis, F.C. Ness and P.O. Ackley have some data, but if you don’t have or can’t find any of these, basic .218 Bee data will fill the bill handily and will yield good results. Keep in mind that this is a small cartridge, so any minor deviation in a powder charge will certainly show up in both the rifle and loaded components.

I used Small Rifle primers like the CCI BR-4 or Remington 7½. Good powder choices range from common Alliant 2400 to IMR 4227 and H4198. A.E. Mashburn would certainly be proud of his contribution to varmint hunters, even in these modern times.

.219 Donaldson Wasp

When I was a boy growing up in New York, the .219 Donaldson was already 20 years old, having been developed by Harvey Donaldson in the same state in 1937. It’s a blown-out .219 Zipper case, with a 28-degree shoulder instead of the Zipper’s 12-degree shoulder. Overall case length is 1.7150 inches.

I purchased a Ruger No. 1 in .218 Bee, then sent it to the Bullberry Barrel Works to be chambered for the .219 Donaldson Wasp. Since the .218 Bee had the correct barrel twist, all Bullberry had to do was to recut the chamber for the new round, then alter the extractor slightly for the larger diameter case. The cases can be formed from .30-30 Win. brass—if you have or can find an RCBS custom shop die set No. 58024, which is no longer available. This three-die set included a pair of forming dies and one forming/trim die.

Fortunately, there are commercial sources of brass. Buffalo Arms sells reformed brass cases in the .219 Donaldson Wasp. E. Arthur Brown does as well, although they’re currently out of stock. Also fortunately, Redding offers .219 Donaldson Wasp dies in its D series, so whether you’re forming your own brass or working with commercial stuff, you can order full-length or neck-size die sets from Redding.

If you are lucky enough to dig up the RCBS forming set to turn .30-30 brass into Donaldson brass, the first die pushes the shoulder back while retaining the .30 caliber neck. The second die takes the outside diameter of the neck from 0.325 inch to 0.290 inch. The last die completes the operation by reducing the outside diameter of the neck to 0.255 inch and the inside neck diameter to 0.227 inch.

After completing these steps, remove the excess length of the neck, chamfer it, and then run it through a full-length die for the proper inside diameter and general cleanup of the parent case.

If you’re fortunate to still have the seventh edition of Hornady’s reloading manual, you can find more details on loads and powders for the .219 Donaldson. An internet search also turned up some downloadable PDF pages from that manual.

Bullet weights from 50 to 55 grains have worked best for me. Historically good powders include IMR 3031, IMR 4064 and IMR 4320, and to them I would add Hodgdon H4895, which has proved to be a good shooter for me—printing three-shot groups of an inch or better.

I found the .219 Donaldson a great vintage cartridge to shoot, and I always enjoyed using it for woodchucks.

.22 K-Hornet

Starting out with a basic .22 Hornet case, Lysle Kilbourn modified this case for more velocity. The most significant difference is the shoulder angle. While the original Hornet has a long, almost taper-like five-degree shoulder, the K-Hornet has a 0.286-inch, 40-degree taper—resulting in more case capacity and about 16 percent more velocity. Other than that and a shorter neck (0.243 inch for the K-Hornet versus 0.386 for the Hornet), the cases are the same: a rim diameter of 0.350 and overall case length of 1.403 inches.

Older Hornet data show that when using a 45-grain bullet and 9.7 grains of Alliant 2400 powder, velocities ran at about 2,600 fps. With the K version, you can raise the payload safely to 11.5 grains of the same powder for 3,000 fps plus.

Keep in mind that the K-Hornet is still a small case—only 13.0 grains of water in my particular cases—so the foregoing advice on adhering to published loads applies. K-Hornet data are not hard to find. Hornady’s 11th edition reloading manual, for example, has plenty of recipes.

For a vehicle to launch this cartridge, by sheer luck I found a 24-inch T/C Contender barrel chambered to the K-Hornet. Brass isn’t commercially available for the K-Hornet, so fire-forming is the way to go. I fired round after round of Winchester .22 Hornet ammo through the Contender K-Hornet barrel. My efforts resulted more than 200 well-defined cases and just one split case. RCBS makes dies (No. 26201) for the K-Hornet. I wanted to neck-size-only my fire-formed cases, and here patience pays off.

What I like to do is smoke these formed cases with the soot of a candle, then run them up and into the die until the base of this die just kisses the top of the shoulder. With the black soot disappearing as you keep advancing up and into the die, this is an easy way to track the progress of resizing only the neck of the case.

I tried a variety of powders, with the best group going to Winchester’s 296 and 680 and Accurate Arms 1680. These groups were all under an inch, perfect for small varmints and all within safe operating pressures.

.220 Wby. Rocket

Weatherby cartridges have always held a fascination for me, and that includes one of Roy Weatherby’s first: the .220 Wby. Rocket. Today you can have it chambered in just about any rifle that was made for the .220 Swift.

Weatherby worked on the Rocket for a couple years before placing it on the market in 1945. It was a good move because the .220 Swift was starting to wane in popularity.

To improve the Swift, Weatherby moved up the shoulder about 0.075 inch for the Rocket, and this new offering held 50.0 grains of water—slightly more than the Swift’s 48.0 grains. It’s not much of a difference for sure, but those who knew Roy Weatherby knew that one-upmanship was his game. And for those who wanted a rifle with a Weatherby cartridge designation engraved on the barrel, any rifle chambered for the .30-06 or the Swift was a strong contender for the Rocket.

I got a Ruger Model 77 II Target chambered in .220 Swift and shipped it to High Tech Custom Rifles to transform it into the .220 Wby. Rocket. There’s no commercially available brass, so I shot more than 100 rounds of Remington 50-grain .220 Swift to fire-form the cases. I wanted to neck-size the cartridge and used an RCBS custom die, No. 55010, to accomplish this. That die is no longer available, but Redding offers dies for the Rocket.

Data on the Rocket are not easy to find, and a call to Weatherby produced one page of loading data from a vintage edition of Tomorrow’s Rifles Today—a promotional book Weatherby published years ago.

The Rocket is a pleasant cartridge to load and shoot, but handloaders should be cautious on some of the older, more out-of-date loading data. Bullets listed were Barnes, Hornady, Speer, Nosler and Sierra—with some Remington 55-grain bullets thrown into the mix. Hodgdon’s H4831sc was the propellant of choice.

My best-shooting load is the Sierra 55-grain boattail over 44.0 grains of IMR 4320. Velocities averaged 4,235 fps in the Ruger’s 26-inch barrel, with groups within 0.5 m.o.a. and no pressure signs. Impressive to say the least.

The .220 Wby. Rocket teamed with the Ruger Target rifle is an interesting combination and certainly within the reach of all. While it will never replace the Swift, it does offer an alternative for those of us who want something different for long-range varmint shooting.

Wildcat .22 centerfires can be fun, adding another dimension to your shooting. They’re a great project that may require a commitment to tasks like fire-forming, and they allow you to go deeper into the science of ballistics as well as the history of U.S. cartridges. See you on the North Forty.

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