The Hornady Number 5 Shell Holder is just what you need to adapt your press to use .300 Whisper Magnum. This .300 Whisper Magnum reloading tool is manufactured to fit Hornady press in addition to being adaptable to most other makes. The Hornady Number 5 Shell Holder Number 5 is perfect for users who need to convert their press to use .300 Whisper Magnum. Hornady Number 5 Shell Holders have precise alignment features and a rounded edge on the shell holder mouth. This number 5 Hornady reloading tool is manufactured to fit standard dies as well as the Hornady Handheld Priming Tool and Cam-Lock Case Trimmer.