The .510 Whisper (13×47mm) is a subsonic rifle cartridge developed by SSK Industries for use in suppressed rifles. It is capable of firing a .51 caliber bullet weighing at roughly .
Overview
The .510 Whisper (13×47mm) is the second of two rounds developed by J. D. Jones with a specific focus on the Thumper concept and subsonic use. Based on the .416 Rigby case, it is a non-belted and bottlenecked cartridge.
Earlier J. D. Jones had already developed the similar .500 Whisper round, which has a roughly longer belted bottlenecked case based on the .378 Weatherby Magnum.
Despite the large bullet, this round is very quiet when using a suppressor due to the subsonic nature of the cartridge. When used with a very high ballistic coefficient bullet, the round only loses about out to over . This gives it more downrange energy at that distance than traditional .30 caliber rounds such as the .308 Winchester and .300 Winchester Magnum. Sako TRG-S test rifles have achieved minute of angle, and better, accuracy with this cartridge at .