The .300 Whisper
(also known as .300 Fireball
- edited to say "these can/do have slightly different dimensions ") is a wildcat cartridge
in the Whisper family
, a group of cartridges
developed in the early 1990s by J.D. Jones of SSK Industries
. It was developed as a multi-purpose cartridge, capable of utilizing relatively lightweight bullets at supersonic
velocities as well as heavier bullets (200–250 grains) at subsonic
The .300 Whisper was originally based on the .221 Fireball
case necked up to .30 caliber. However, avid reloaders have found the .223 Remington
or 5.56×45 mm NATO
works well when shortened and resized to .30 caliber. Firing in the .300 Whisper chamber
results in a slightly sharper shoulder. Magnum
pistol powders such as H110 work well for subsonic loads. Sierra 240 grain (16 g) jacketed bullets work well if the barrel
has a 1:8 twist
. Barrels with a 1:10 twist will stabilize 220 grain (14 g) bullets at subsonic speeds. 125 grain (8 g) bullets will reach 2400 ft/s (730 m/s).
There are a few points to be considered regarding the utility of the .300 Whisper:
- Supersonic loads are capable of matching ballistics of the 7.62x39mm and the .30-30 Winchester, making the .300 Whisper very capable as a short range deer hunting cartridge.
- The use of heavy bullets, along with the low powder weight and small case capacity, make the......