Whisper Family of Firearm Cartridges
Encyclopedia
The Whisper family of firearm cartridges is a group of wildcat cartridge
s developed in the early 1990s by J.D. Jones of SSK Industries. The Whisper Family was developed as a line of accurate, multi-purpose cartridges using relatively heavy rifle
bullets for a given caliber in subsonic
loads. The intention was to create an extremely accurate cartridge family for military, police, competition and specialized hunting markets that could also be easily sound suppressed.
While all cartridges in the Whisper family must be capable of accuracy using subsonic loads, most of the smaller caliber cartridges of the family (.308" and under) are also capable of being loaded to supersonic
velocities using relatively lightweight bullets for their caliber, increasing their utility.
(1128 ft/s at 70°F) to avoid the sonic crack caused by the bullet breaking the sound barrier
. This allows the cartridge to be sound suppressed
relatively easily. Additionally, in some cases, subsonic loads are often intended to avoid the turbulent transonic
zone entirely, maximizing potential accuracy.
Yet another consideration of the Whisper Family design is that all of the cartridges are based on existing cases that utilize common case head dimensions. This allows rifles with common bolt face dimensions to be converted to a Whisper cartridge fairly easily, often requiring only the rifle's action to be re-barreled. There are four "series" within the Whisper Family, each using a different parent case.
of SSK Industries. In order to sidestep this branding (and/or any licensing fees required to use the "Whisper" name legally), other manufacturers tend to use different names for cartridges in the Whisper family. For example, the .300 Whisper (the most popular cartridge of the family) is often called ".300 Fireball" or ".300-221".
Wildcat cartridge
A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...
s developed in the early 1990s by J.D. Jones of SSK Industries. The Whisper Family was developed as a line of accurate, multi-purpose cartridges using relatively heavy rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
bullets for a given caliber in subsonic
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
loads. The intention was to create an extremely accurate cartridge family for military, police, competition and specialized hunting markets that could also be easily sound suppressed.
While all cartridges in the Whisper family must be capable of accuracy using subsonic loads, most of the smaller caliber cartridges of the family (.308" and under) are also capable of being loaded to supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
velocities using relatively lightweight bullets for their caliber, increasing their utility.
Subsonic cartridges
A subsonic cartridge is designed to fire its bullets at velocities slower than the speed of soundSpeed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
(1128 ft/s at 70°F) to avoid the sonic crack caused by the bullet breaking the sound barrier
Sound barrier
The sound barrier, in aerodynamics, is the point at which an aircraft moves from transonic to supersonic speed. The term, which occasionally has other meanings, came into use during World War II, when a number of aircraft started to encounter the effects of compressibility, a collection of several...
. This allows the cartridge to be sound suppressed
Suppressor
A suppressor, sound suppressor, sound moderator, or silencer, is a device attached to or part of the barrel of a firearm which reduces the amount of noise and flash generated by firing the weapon....
relatively easily. Additionally, in some cases, subsonic loads are often intended to avoid the turbulent transonic
Transonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...
zone entirely, maximizing potential accuracy.
Whisper Cartridge Cases
| Cartridge | Parent Case |
|---|---|
| 6mm Whisper | .221 Fireball |
| 6.5mm Whisper | .221 Fireball |
| 7mm Whisper | .221 Fireball |
| .300 Whisper .300 Whisper The .300 Whisper is a wildcat cartridge in the Whisper family, a group of cartridges developed in the early 1990s by J.D. Jones of SSK Industries... |
.221 Fireball |
| .338 Whisper #2 | .221 Fireball |
| .338 Whisper .338 Whisper The .338 Whisper is a wildcat cartridgein the Whisper family, a group of cartridges developed in the early 1990s by J.D. Jones of SSK Industries. Unlike the smaller caliber cartridges in the Whisper family, loads for the .338 Whisper are mainly limited to subsonic velocities... |
7mm Bench Rest |
| .375 Whisper | 7mm Bench Rest |
| .416 Whisper | 7mm Bench Rest |
| .458 Whisper | .458 Winchester magnum .458 Winchester Magnum The .458 Winchester Magnum is a belted, straight-taper cased, dangerous game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express... |
| .500 Whisper | .460 Weatherby Magnum .460 Weatherby Magnum The .460 Weatherby Magnum is a belted, bottlenecked rifle cartridge, developed by Roy Weatherby in 1957. The cartridge is based on the .378 Weatherby Magnum necked up to accept the bullet. The original .378 Weatherby Magnum parent case was inspired by the .416 Rigby... |
| .510 Whisper .510 Whisper The .510 Whisper was developed by SSK Industries to shoot .510 bullets in a suppressed rifle. The case is based on the .338 Lapua Magnum cut down to . Neck wall thickness is reduced to and a small shoulder is cut into the body for head spacing... |
.338 Lapua Mag .338 Lapua The .338 Lapua Magnum is a specialized rimless bottlenecked centerfire cartridge developed for military long-range sniper rifles. The Afghanistan War and Iraq War made it a combat-proven round with ready and substantial ammunition availability... |
Yet another consideration of the Whisper Family design is that all of the cartridges are based on existing cases that utilize common case head dimensions. This allows rifles with common bolt face dimensions to be converted to a Whisper cartridge fairly easily, often requiring only the rifle's action to be re-barreled. There are four "series" within the Whisper Family, each using a different parent case.
- The .221 Fireball case shares the same case head dimensions as the commercial .223 Remington.223 RemingtonThe .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56×45mm NATO military cartridge. The name is commonly pronounced either two-two-three or two-twenty-three. It is loaded with a diameter, jacketed bullet, with weights ranging from , though the most common...
and military 5.56x45mm cartridges. (0.375")
- The 7mm Remington Bench Rest case shares the same case head dimensions as the commercial .308 Winchester.308 WinchesterThe .308 Winchester is a rifle cartridge and is the commercial cartridge upon which the military 7.62x51mm NATO centerfire cartridge is based. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65...
(as well as other cartridges based on that case; .243 Winchester.243 WinchesterThe .243 Winchester is a popular sporting rifle cartridge. Initially designed as a varmint round, it is now more frequently used on medium to large game such as whitetail deer, mule deer, pronghorn, wild hogs, and even black bear and caribou...
, .260 Remington.260 RemingtonThe .260 Remington cartridge was introduced by Remington in 1997. Many wildcat cartridges based on the .308 Winchester case had existed for years before Remington standardized this round...
, 7mm-08 Remington, etc...) and military 7.62×51 NATO cartridges. (0.470")
- The .460 Weatherby Magnum has a case head diameter unique to the large Weatherby belted magnum cases. Few other cartridges use this case head size (or something close, like the .416 Rigby). This tends to mean that rifles capable of being converted are somewhat less available or are based on expensive custom actions. Also, cases for forming tend to be very expensive. (0.580")
- The .338 Lapua Magnum case also has a fairly unique case head diameter. However, the vast majority of rifles chambered for the .338 Lapua Magnum are bolt actions and as such can be chambered in .510 Whisper via a relatively simple re-barrelling. As the manufacture of .338 Lapua Magnum ammunition would appear to be going nowhere but up (due to several militaries adopting it for their sniper rifles), this may be a reason behind the development of a Whisper cartridge based on its case. More available and more economical brass. (0.590")
Mini and Micro Whispers
There are also two little-known cartridges of the Whisper Family based on handgun cartridge cases. These are the 7.62 Micro Whisper, based on the .30 Luger case; and the 7.63 Mini-Whisper, based on the .30 Mauser case. Like the rest of the Whisper Family, these two cartridges are designed to fire rifle bullets at subsonic velocities.Trademark
"Whisper" is a registered trademarkTrademark
A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
of SSK Industries. In order to sidestep this branding (and/or any licensing fees required to use the "Whisper" name legally), other manufacturers tend to use different names for cartridges in the Whisper family. For example, the .300 Whisper (the most popular cartridge of the family) is often called ".300 Fireball" or ".300-221".