Gun Digest

.300 Blackout Vs .300 Whisper: Is There A Difference?

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Both kick out .30-caliber bullets, are pleasant shooters and can be kept quiet as a church mouse, so is there really any difference between the .300 Blackout and its predecessor the .300 Whisper?

Development Of The .300 Whisper

The beginning of the subsonic revolution in ARs came to us from J.D. Jones. To call him a prolific inventor is to use “prolific” lightly.

He has always endeavored to expand the borders of firearms performance, from the smallest to the largest. The .300 Whisper was his AR-15 cartridge for quiet shooting. The idea was simple: take a .223 case, expand the neck to hold a .30-caliber bullet, shorten it so the neck would hold the bullet at the proper place, and fit it all into an AR-15 magazine. A shortcut would be to take the .221 Fireball case, and neck it out to .30. The Fireball itself was essentially just a shortened .223, meant for use in single-shot bolt-action pistols, primarily the Remington XP100. It was the varminting answer to “How do I use a handgun to shoot varmints?”

J.D. was aided in this work by the continuing efforts of rifle target shooters. When I began shooting in the early 1970s, the bullets available for .30 rifles for target shooting were not many. You could find a 168-grain match boat tail. You could, if you were lucky and persistent, score a supply of 175-grain FMJ-BT bullets, which were used for decades before by the military.

Heavier than that, there were only hunting bullets. There were 180-grain soft points, and 220 FMJ or soft-point bullets, but they were round-nosed, and meant for use on large game. You’d have the 220s loaded in your .30-06 or .300 H&H, for use on bear, moose or elk on a hunt in Alaska or Canada.

But long-range target shooters wanted more. For long-distance shooting, the competitor has two problems: distance and wind. Distance is easy, as the targets are a known distance away, and that distance does not change. Wind, however, does.

The range of bullets the .300 Blackout and Whisper can digest is impressive. From a 110-grain soft point to a 240-grain match boat tail, you can load anything that will fit the chamber and throat.

If we assume a bullet design has the same ogive, and boat tail, then the only way to change weight is to make it longer. This is good, because a longer and heavier bullet will have a larger ballistic coefficient, or BC. BC is a measure of a bullet’s drag, compared to a theoretical object that is a standard. The higher the BC, the more efficiently a bullet passes through the air.

We’re getting a bit involved here, so stick with me. For any given cartridge, operating at a certain pressure, adding weight to a bullet means you have less velocity. You simply cannot push a (to use as an example) 168-grain .30 bullet and a 240-grain .30 bullet at the same speed. The 240, in any given cartridge, has to be going slower, simply because the pressure limit of the cartridge determines the maximum amount of energy you can use to push the bullet.

Target shooters don’t care. A bullet with a higher BC loses less velocity as it goes downrange, so the net is not to lose as much when it reaches to the target. The real boon for target shooters is that a higher-BC bullet is less affected by wind.

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