.510 Whisper

.510 Whisper
Type Rifle
Place of origin USA
Production history
Designer SSK Industries
Specifications
Parent case .338 Lapua Magnum
Case type Rimless, bottleneck
Bullet diameter .510 in (13.0 mm)
Neck diameter .549 in (13.9 mm)
Shoulder diameter .587 in (14.9 mm)
Base diameter .587 in (14.9 mm)
Rim diameter .588 in (14.9 mm)
Case length 1.875 in (47.6 mm)
Overall length 3.34 in (85 mm)
Ballistic performance
Bullet mass/type Velocity Energy
750 gr (49 g) AMax 1,050 ft/s (320 m/s) 1,837 ft·lbf (2,491 J)
Source(s): SSK Industries [1]

The .510 Whisper is a subsonic rifle cartridge developed by SSK Industries for use in suppressed rifles.[2] It fires a .51-caliber bullet weighing 750 gr (49 g) at roughly 1,050 ft/s (320 m/s).

Overview

Despite the large bullet, this round is very quiet, similar to the noise from a .22 Short when used with a suppressor. When used with a very high ballistic coefficient bullet, the round only loses about 100 ft/s (30 m/s) out to over 500 yards. This gives it more downrange energy at that distance than traditional .30 caliber rounds such as the .308 Winchester and .300 Winchester Magnum.[3] SAKO TRG-S test rifles have achieved MOA and better accuracy with this cartridge at 600 yards.[2]

Powders such as H110, 4227, or surplus WC820 are well suited for subsonic loads and give a low standard deviation. Necessary components such as barrels, reloading dies, etc. are available from SSK. Sako TRG-S actions are most often converted to this caliber. The Thompson Center Encore is also suitable, but is rather lightweight for shooting this heavy recoiling cartridge, especially when using 950-grain (62 g) bullets.

Design

The case of the .510 Whisper is based on the .338 Lapua Magnum that has been trimmed down to a length of 1.875 in (47.6 mm) and necked-down to accept a .510 in (13.0 mm) diameter bullet. Neck wall thickness is reduced to 0.013 in (0.33 mm) and a small shoulder is cut into the body for headspacing. Overall length of the loaded round is about 3.34 in (85 mm).

See also

References

  1. ↑ SSK Industries homepage
  2. 1 2 Barnes, Frank C. (2006) [1965]. Skinner, Stan, ed. Cartridges of the World (11th ed.). Iola, WI: Gun Digest Books. p. 282. ISBN 0-89689-297-2.
  3. ↑ "Whisper cartridges" by Lukas Kruesi, New Zealand Guns & Hunting, September/October 2003
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