.300 Winchester Short Magnum

Specifications

The overall cartridge length is 72.6 mm. The cartridge case length is 53.34 mm. The bullet diameter is .308 in (7.82 mm), which is common to U.S. .30 caliber cartridges. The principle at work in the short magnum cartridge is the fitting of larger volumes of powder in closer proximity to the primer's flash hole, resulting in more-uniform ignition, thereby generating essentially the same ballistic performance as long-action magnums with less powder, and less recoil. The .300 WSM has a case capacity of 80 grains. The .30-06 Springfield holds 69 grains; .308 Winchester holds 56 grains; .30-30 Winchester holds 45 grains; .300 Winchester Magnum has a case capacity of 93.8 grains. While providing ballistic performance nearly identical to that of the .300 Winchester Magnum, 300 WSM does this with about 14 grains less powder. The .300 WSM also head-spaces off of the case shoulder, versus the older .300 Winchester Magnum's belted head space design.

The advantage to this round is the ballistic performance is nearly identical to the .300 Winchester Magnum in a lighter rifle with a shorter action burning 8 - 10% less gunpowder. A disadvantage of cartridge case designs with relatively large case head diameters lies in relatively high bolt thrust levels exerted on the locking mechanism of the employed firearm. Also, in small ring actions the larger chamber diameter removes more steel from the barrel tenon, making it weaker radially. The short, squat design of the cartridge also can cause feeding issues, especially in rifles whose magazine follower isn't at a very specific angle, leading to rounds not being properly fed out of the magazine and engaged by the bolt carrier.

Use

The .300 WSM is adequate for hunting all types of big game in North America including (but not limited to): moose, black bear, brown bear, elk, black-tailed deer, mule deer, and white-tailed deer in forests and plains where long range, flat shots are necessary. The .300 WSM is also used in benchrest shooting, in 2021 a .300 WSM was used to break the world record for best 10-shot grouping at 1,000 yards at a benchrest competition in Texas.

The .300 WSM has a standard bullet diameter of .308 in (7.62 mm) and takes advantage of the numerous bullet options available in that caliber.

Warnings

The 300 WSM is a Delta L problem cartridge, meaning it can present unexpected chambering and/or feeding problems. The Delta L problem article explains this problem in more detail. The .300 Remington Short Action Ultra Magnum has very similar cartridge dimensions but is not interchangeable.

Muzzle velocity

• 165 gr (10.69 g) Full Metal Jacket (FMJ): 3,223 ft/s (982 m/s)
• 180 gr (11.66 g) Full Metal Jacket (FMJ): 3,095 ft/s (943 m/s)
  • Muzzle velocity varies slightly between individual loads and bullet types.

Comparison

Legacy

Of all the short magnums that came out in the 2000s decade the .300 WSM, along with the .270 WSM, are one of the few that have stood the test of time and still have rifles being made for them as of 2025. Both Remington and Ruger no longer manufacture rifles chambered for their proprietary Remington Short Action Ultra Magnum and Ruger Compact Magnum cartridges, although ammunition is still available for them albeit with a limited selection. Among Winchester's short magnums, rifles chambered for the 7mm WSM are no longer made, and the .325 WSM has a limited current production from Winchester. However both the .270 WSM and .300 WSM can be found in a variety of models from major firearms manufacturers including: Remington's Model 700 CDL SF, SPS & SPS Stainless; Savage's Model 110 Apex Hunter, Apex Storm, Long Range Hunter, & High Country; and Winchester's Model 70 Classic Featherweight, Extreme Timber, Extreme Tungsten, Extreme Weather, Long Range & Super Grade; all of which are still chambered for the .270 WSM and .300 WSM.

References

References

1. [http://www.chuckhawks.com/subscribers/rifle_cartridge_page/300WSM.htm The 300 WSM (Winchester Short Magnum) by Chuck Hawks (subscriptions req)]
2. "300 Winchester Short Magnum (WSM) Load Data". Nosler Inc..
3. (26 March 2022). "Short Magnums: A Short Story or Here to Stay?". Haas Outdoor Inc..
4. ".30-06 Springfield Load Data". Nosler Inc..
5. ".308 Winchester Load Data". Nosler Inc..
6. ".30-30 Winchester Load Data". Nosler Inc..
7. ".300 Winchester Magnum Load Data". Nosler Inc..
8. (9 March 2018). "Head to Head: .300 Win. Mag. vs. .300 WSM". National Rifle Association.
9. ".300 Winchester Short Magnum".
10. (3 May 2023). ".30-06 Springfield vs. .300 Winchester Short Magnum". MeatEater Inc..
11. ".300 WSM Rifles".
12. (8 April 2021). "World Record NBRSA 1000-Yard 10-Shot Benchrest Group Achieved". The Firearm Blog.
13. "New 1,000 Yard World Record Set With Berger Bullets". Berger Ammo.
14. (2023). ".308 Winchester: How To Pick The Right Bullet Weight". Amdep Holdings, LLC.
15. (20 October 2022). "Why the .308 Winchester Will Never Die". Recurrent Inc..
16. "Load guide for rifle and handgun". Accurate Powders.
17. "Nosler 7mm Remington Short Action Ultra Magnum ammo". Nosler Inc..
18. ".338 Ruger Compact Magnum ammo". Palmetto State Armory.
19. "Model 700". © RemArms LLC.
20. "Savage .300 WSM". © Savage Arms, Inc..
21. "Model 70 Short Magnums". Winchester Repeating Arms.