When compared to .300 AAC Blackout Steve Johnson’s article in American Hunter sums it up best: Given the fact that major manufacturers such as Hornady are building ammunition headstamped .300 Whisper and recommending it for use in either platform—in addition to producing reloading dies that are marked “300 Whisper/Blackout” and Smith & Wesson stamps the barrel of its M&P-15 Whisper barrels with: “300 Whisper/300 AAC Blackout” it is safe to say that differences are minimal.

However, reloaders have found the .223 Remington or 5.56×45mm NATO works well when shortened and resized to .30 caliber.

There are a few points regarding the utility of the .300 Whisper: In addition to special applications in suppressed firearms, the .300 Whisper has become popular with metallic silhouette shooters due to its low recoil, good long range performance, and high accuracy.

[3] In order to sidestep this branding and/or avoid licensing fees required to use the "Whisper" name legally, other manufacturers tend to use different names for identical or highly similar cartridges.

The .300 AAC Blackout has succeeded as a commercial cartridge while the Whisper never achieved wide acceptance.