The .221 Fireball was created in 1959 as the initial chambering for Remington’s new, unique, “space-age” XP-100 bolt-action pistol. (Photo courtesy of Lane Pearce)
September 20, 2022
By Lane Pearce
Most folks think that Gaston Glock introduced pistols with plastic receivers in the mid-1980s. Actually, Remington introduced a bolt-action, single-shot handgun with an injection-molded Zytel stock more than 20 years earlier (1963). Granted, the XP-100’s receiver was not plastic—neither is the Glock’s—but the XP-100 was definitely not a conventional handgun. It was commonly identified as something the sci-fi superhero Buck Rogers might have used as he traveled around the universe fighting evil.
Obviously, such a uniquely exotic firearm warranted a specifically designed cartridge. In this case, it’s the .221 Fireball. Typically referred to as being derived from the .222 Remington, the .221 Fireball is more aptly described as a shortened .223 Remington. The Fireball’s case length is about 0.38 inch less than the .223’s, with all other features the same. The two rounds even share the same SAAMI Maximum Average Pressure (MAP) criteria (52,000 CUP). Having only 60 percent of its parent’s case capacity, the .221 Fireball can achieve close to 90 percent of the .223’s ballistic performance. The .222 Rem.’s MAP is 46,000 CUP, so when chambered in rifles with equal-length barrels, the .221 Fireball can often match the .222’s ballistics.
Handloading the .221 Fireball can be summed up with a few comments. A plethora of load data is available in several reliable load manuals. Also, there are myriad .22-caliber varmint and target bullets (35 to 53 grains) and at least a dozen compatible propellants. Any standard or match Small Rifle primer will reliably and consistently ignite the typical 15- to 20-grain powder charges. Reloading dies are cataloged by all major suppliers.
Lane found that resting the grip’s butt and the fore-end on shooting bags improved his ability to shoot the XP-100 accurately at long distances. (Photo courtesy of Lane Pearce) The reloading process for the Fireball is the same as you would follow for any bottlenecked, rimless rifle cartridge. Just remember the case is relatively small, and a little lube goes a long way. Seating tiny bullets in a rather short case is tricky, so I set up my single-stage RCBS press with an extended shellholder and RCBS micrometer adjustable competition-style seating die. It features a port on the side where you can readily drop the bullet into position instead of trying to keep it aligned while guiding it into the bottom of a conventional seating die.
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The XP-100 is a single shot, so while the recommended cartridge overall length is nominally 1.83 inches, you can vary that to tune the accuracy of your handloads. Maximum COL is limited only by two factors: 1.) If the round will fit in the chamber; and 2.) If the bullet is seated deep enough in the case neck to stay securely in place before it’s loaded into the chamber.
The original XP-100’s design is not at all conducive to achieving sterling accuracy. The bottom of the ambidextrous grip approximates an ellipsoid shape, i.e., it’s curved forward to back, side to side, and in between. Which means when you place the butt on a rest, any force applied to the centrally located “joystick” grip will instantly alter the pistol’s orientation. Resting the fore-end and the butt only reduces the single-point rest “3D bobble” to a two-point support.
Imagine trying to steady the handgun while maintaining proper alignment of your eye with a high-magnification, extended-eye-relief optic and manipulating a slightly creepy trigger connected to the sear by a transfer bar that is several inches long. Plus, unlike the relatively stable platform of a much heavier benchrest rifle, if you’re a right-handed shooter, as I am, you must relinquish your grip between shots to manipulate the bolt and then reacquire the appropriate firing stance. A later version, the XP-100R, featured a longer barrel, more caliber choices, and a grip that was relocated under the action with a conventional trigger arrangement. I’ve never fired one, but it had to be easier to shoot.
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Notwithstanding these comments, my XP-100 is capable of excellent accuracy. For example, one of my handloads put four out of five shots at 100 yards into a group that measured a half-inch and will drop a like percentage of ground squirrels all the way out to 200 yards if the shooter can control the scope reticle’s position.
The .221 Fireball is not likely to be found on a top-50 most popular cartridge list. It’s truly a niche round, but that doesn’t mean wildcatters haven’t noticed it. J.D. Jones necked it up and developed the .300 Whisper to launch heavy-for-caliber bullets at subsonic velocities. The .17 Mach IV and .20 VarTarg were also derived from the parent .221 Fireball case. Remington later tweaked the .17 Mach IV dimensions and introduced the .17 Fireball. It can fire tiny, lightweight bullets even faster than its .22-caliber brother can.
The original Zytel-stocked .221 Fireball XP-100 was discontinued in the mid-1980s, while the XP-100R model lasted until just after Y2K. And as a trivia note, the original round was labeled the .221 Fire Ball (two words). As time passed, the words merged together. Powders like Accurate 1680 and IMR 4198 amply demonstrate why it was named fireball!
