.300 Remington Short Action Ultra Magnum (also known as 300 RSAUM, 300 RSUM or 300 Rem SAUM) is a .30 caliber

Caliber

In guns including firearms, caliber or calibre is the approximate internal diameter of the barrel in relation to the diameter of the projectile used in it....

 short magnum

Magnum

Magnum may refer to several things:* Moses Magnum, a Marvel Comics villain*Magnum, P.I., a television series** Thomas Magnum, the lead character...

 cartridge

Cartridge (firearms)

A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 that was put on the market shortly after Winchester released its 300 WSM round in 2001.

Performance

The 300 RSAUM's ballistics are similar to 300 Win Mag

.300 Winchester Magnum

The .300 Winchester Magnum is a popular, belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms Company in 1963 as a member of the family of Winchester Magnum cartridges. The .300 Winchester Magnum is a magnum cartridge designed to fit in a standard length...

 and 300 WSM. The difference in ballistics between the WSM and RSAUM are fairly minuscule.

Muzzle velocity

• 10.69 g (165 gr) Full Metal Jacket(FMJ): 3,075 ft/s
• 11.66 g (180 gr) Full Metal Jacket(FMJ): 2,960 ft/s

Comparisons

• The WSM has slightly more case capacity and thus, slightly more velocity
• The WSM is more popular and more ammo and handloading
  Handloading
  Handloading or reloading is the process of loading firearm cartridges or shotgun shells by assembling the individual components , rather than purchasing completely assembled, factory-loaded cartridges...
  
   data are available

.300 RSAUM performance comparisons

Cartridge	Bullet Weight	Muzzle velocity Muzzle velocity Muzzle velocity is the speed a projectile has at the moment it leaves the muzzle of the gun. Muzzle velocities range from approximately to in black powder muskets , to more than in modern rifles with high-performance cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns...	Muzzle energy Muzzle energy Muzzle energy is the kinetic energy of a bullet as it is expelled from the muzzle of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load...
.30-06 Springfield .30-06 Springfield The .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...	200	2569	2932
.300 RSAUM	200	2790	3458
.300 WSM	200	2822	3538
.300 Win Mag .300 Winchester Magnum The .300 Winchester Magnum is a popular, belted, bottlenecked magnum rifle cartridge that was introduced by Winchester Repeating Arms Company in 1963 as a member of the family of Winchester Magnum cartridges. The .300 Winchester Magnum is a magnum cartridge designed to fit in a standard length...	200	2877	3677
.300 H&H Magnum .300 H&H Magnum The .300 H&H Magnum Cartridge was introduced by the British company Holland & Holland as the Super-Thirty in June, 1925. The case was belted like the .375 H&H Magnum, and is based on the same case, as also is the .244 H&H Magnum. The belt is for headspace as the cases' shoulders have a narrow...	200	2913	3769
.300 Wby Mag .300 Weatherby Magnum The .300 Weatherby Magnum is a .30 caliber rifle cartridge created by Roy Weatherby in 1944 and produced by Weatherby. It has become the most popular of all the Weatherby cartridges.-Background:...	200	2987	3963
.300 RUM .300 Remington Ultra Magnum The .300 Remington Ultra Magnum, also known as the .300 Ultra Mag or .300 RUM is a 7.62 mm caliber rifle cartridge , 7.62x72mm, or .30 caliber rifle cartridge introduced by Remington Arms in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums...	200	3154	4419

See also

• .300 Remington Ultra Magnum
  .300 Remington Ultra Magnum
  The .300 Remington Ultra Magnum, also known as the .300 Ultra Mag or .300 RUM is a 7.62 mm caliber rifle cartridge , 7.62x72mm, or .30 caliber rifle cartridge introduced by Remington Arms in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums...
  
  
• 7 mm caliber
  7 mm caliber
  This article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge....
  
  
• List of firearms
• List of rifle cartridges
• List of individual weapons of the U.S. Armed Forces