The .221 Fireball was developed in 1963 by Remington for use in the predecessor to the XP-100 pistol. Again something we know. It is unknown who first necked up the .221 Fireball to .30 cal., but the purpose was most likely metallic silhouette shooting, which was very popular at the time.
Two other things that we know: The .300 Whisper was developed, documented and trademark-
registered in 1992 by J.D. Jones. The .300 AAC Blackout was developed, documented and presented to SAAMI by Advanced Armament Corporation in 2009. Hornady Mfg. Co.—a SAAMI member company—recommends its .300 Whisper ammunition in firearms chambered for either .300 Whisper or .300 AAC Blackout. Confused yet?
Hornady is one of the most respected ammunition manufacturers in the world and, as I am a former Hornady employee, I know that it wouldn’t recommend such a practice unless it had thoroughly tested for safety, reliability and function. When Hornady says its ammunition is good to go in the .300 Whisper and .300 AAC Blackout, you can take that to the bank.
J.D. Jones is likely responsible for the vast majority of the work in the field of subsonic ballistics during the past 20-plus years, and he is unofficially considered by many the father of modern subsonic ballistics. Jones owns SSK Industries and, among other accomplishments, developed the series of cartridges with both “JDJ” and “Whisper” designations. Jones developed “Whisper” cartridges from 6 mm to .50 cal. and everything in between. The .300 Whisper was the first in the series, developed in 1992.
My first experience with the .300 Whisper came when I was developing load data for the 5th Edition Hornady Handbook of Cartridge Reloading more than a decade ago. I was impressed enough to purchase an SSK barrel in .300 Whisper for my T/C Contender. It had the ability to shoot projectiles from 0.308" pistol bullets all the way up to heavy match rifle bullets, such as the Sierra 240-gr. BTHP MatchKing and later the 208-gr. A-MAX, which I have used to take game including whitetail deer. Jones explained that the .300 Whisper really shined when it was chambered in M16/AR-15 platform rifles, especially short-barreled rifles, as it acts more like a pistol cartridge than a rifle cartridge.
In 2009, word spread that AAC was bringing out a cartridge similar to the .300 Whisper and calling it the .300 Blackout. Enter the controversy. I called on Robert Silvers, director of research and development for AAC. He has been willing to share drawings, specifications, etc., and even forwarded the SAAMI-approved chamber reamer drawing of the .300 AAC Blackout reprinted below. Silvers and AAC have been forthcoming and helpful with any and all information about the .300 Blackout. If I had not had the background that I did with the .300 Whisper, nor a ringside seat inside the industry as a Hornady employee, I would have readily assumed that the .300 AAC Blackout is a completely different cartridge than the .300 Whisper. A large percentage of firearm enthusiasts believe that is the case, and it simply is not.
Why the .300 Whisper and the .300 AAC Blackout? To answer that I interviewed the two men responsible for the two most popular versions of the .30-.221 Fireball—SSK’s Jones and AAC’s Silvers. According to Jones, the .300 Whisper was developed in the Fall of 1992 with the first-use copyright on Nov. 12, 1992. The Whisper’s development “Simply boils down to my interest in developing ‘new’ cartridges and applications. Up to the point when I invented the .300 Whisper I don’t know of anyone who gave much thought to accuracy in a subsonic, silenced [arm] in this country,” stated Jones. “To be successful I thought the cartridge had to have both heavy-bullet, subsonic silenced and light-bullet, moderately high-velocity capabilities; be useful in the M16, single-shots, [and] bolt-actions; easily silenced with recreational shooting such as metallic silhouette and moderate big-game capabilities—such as pigs and deer—with exceptionally low recoil and decent accuracy. The .221 Fireball cartridge case was the right length, readily available and easily neck expanded to .30 caliber. The .223 case was looked at and found to present many problems due to its many variations in capacity, wall dimensions giving unacceptable neck wall thickness variations, in addition to being a tough trim job. Expanding neck dimensions to accommodate all of these variations would result in sloppy neck dimensions and in accuracy and sizing problems. An overly thick neck can allow a semi-automatic to chamber a round almost fully but not enough to fire.”
As to the development of the .300 Blackout, Silvers said: “We started development in 2009, but most of the work was done in 2010. A military customer wanted a way to be able to shoot .30-cal. bullets from an M4 platform while using normal bolts and magazines, and without losing the full 30-round capacity of standard magazines. They also wanted a source for ammunition made to their specs. We could not have just used .300-.221 or .300 Whisper because Remington is a SAAMI company, and will only load ammunition that is a SAAMI-standard cartridge. We had to take the .300-221 wildcat concept, determine the final specs for it, and submit it to SAAMI. We did that, and called it the .300 AAC Blackout (.300 BLK).”
Reamer/Chamber Drawings (Click to Enlarge)