Skip to main content

25 WSSM Load Data

25 WSSM Load Data
An array of .25-caliber bullets is available to the handloader. These are the ones tested here: (from left) Sierra 87-gr. SP; Barnes 100-gr. TS-X BT; Nosler 100-gr. Partition; Speer 100-gr. Hot-Cor; Sierra 100-gr. SPT; Swift 100-gr. A-Frame; Swift 100-gr. Scirocco II; Hornady 110-gr. InterBond; Nosler 110-gr. AccuBond; Nosler 115-gr. BT; Sierra 117-gr. SBT; Hornady 117-gr. BTSP; Nosler 120-gr. Partition; Speer 120-grain Grand Slam; Speer 120-gr. Hot-Cor; and Swift 120-gr. A-Frame.

An array of .25-caliber bullets is available reloading .25 WSSM ammo. These are the ones tested here: (from left) Sierra 87-gr. SP; Barnes 100-gr. TS-X BT; Nosler 100-gr. Partition; Speer 100-gr. Hot-Cor; Sierra 100-gr. SPT; Swift 100-gr. A-Frame; Swift 100-gr. Scirocco II; Hornady 110-gr. InterBond; Nosler 110-gr. AccuBond; Nosler 115-gr. BT; Sierra 117-gr. SBT; Hornady 117-gr. BTSP; Nosler 120-gr. Partition; Speer 120-grain Grand Slam; Speer 120-gr. Hot-Cor; and Swift 120-gr. A-Frame.

Back when the Earth was flat and I still had hair, the term "short magnum" meant a cartridge based on the .300 H&H Magnum case whacked off to about 2 ½ inches. No more. Nowadays, there are lots of "short magnums" with case lengths and diameters all over the place. In 2001 Winchester introduced the .300 WSM, followed soon by the .270, 7mm and .325 WSMs. These are loosely based on the .404 Jeffery case shortened to 2.1 inches, and they have a body diameter of .555 inch - bigger than the belt of the older H&H case.

In the mid-1990s Winchester stunned the shooting world with another trio of short magnums in .223, .243 and .25. Called Winchester Super Short Magnums, their cases are the same diameter as the WSMs, but only 1.670 inches in length.

The .25 WSSM was designed to duplicate the .25-06, and in some instance, it does. With 100- to 120-grain bullets, velocities approach that threshold, but the newer cartridge can do so only by operating at higher pressures - 65,000 psi compared with the .25-06's 53,000 psi. The main vehicles for the .25 WSSM were the Browning A-Bolt and Winchester Model 70. Unfortunately, both have been discontinued. Thus, the seeker of a bolt-action .25 WSSM must scour the used-gun market.


Olympic Arms Company produces an extensive line of ARs in a host of calibers, and its Model K8-MAG is offered in the three WSSMs noted above. Our test gun was a production K8-MAG in .25 WSSM sporting a 24-inch barrel with a 1:10 twist.


The K8-MAG comes with a 10-round magazine, which is actually a modified 5.56 AR magazine, and it functioned 100 percent - as long as the cartridge's OAL was right.

Maximum length for the .25 WSSM is roughly 2.700 inches - obviously too long for an AR magazine - so bullets in handloads must be seated to 2 ¼ inches to feed properly. And, no, factory loads at 2.34 inches in length won't work in the K8-MAG. This is, of course, of little consequence for the handloader. All of the test loads reported here were loaded to 2 ¼ inches, and functioning was 100 percent.

Handloading the .25 WSSM is about like any other bottlenecked rifle round. The only problem that surfaced during testing was case life. The drastic reduction in diameter required to form the .25 WSSM case seriously work-hardens the neck and shoulder areas, and split cases are frequent after a few firings.

One could easily solve this problem by annealing, of course. It should also be noted that the necks of this case are somewhat thicker (at .021 inch) than some other .25-caliber cartridges, such as the .257 Roberts and .25-06 at .0165 inch. This makes seating bullets in a new case difficult unless the inside of the case neck is polished and/or lubed prior to bullet seating. Lightly chamfering the case mouth is also recommended.


[nggallery id=183]

Now that we've gotten that out of the way, let's get down to loading. I used a set of Redding dies to prepare the test loads. The correct shell holder is the same one used for the WSMs. Don't over-lube, or dents will occur in the case's 30-degree shoulder. Even though the .25 WSSM is a "magnum," its modest case capacity really calls for standard primers. I used Winchester WLRs for all loads save one, which was started by CCI-250 magnum caps, and all worked perfectly.

A wide variety of powders such as H-4350, Reloders 17 and 19, Varget, Hunter and W-760 worked well in the .25 WSSM. IMR-4007SSC was a standout in the semiauto with several loads.


While this cartridge can certainty be used for varmints, probably few will lay down an extended barrage in a dog town with it. For low-volume, long-range shooting, the 87-grain Sierra SPT at 3,036 fps over 47.5 grains of Big Game makes a serious coyote load, however.

The .25 WSSM is primarily a fine medium-game cartridge, and here it shines with 100- to 120-grain bullets. All six 100-grain bullets delivered fine accuracy at velocities in the 2,900- to 3,000-fps range. The Speer Hot-Cor with 47.0 grains of H-4350 was barely shy of the 3,000 fps mark and turned in 1¼ -inch groups. Hornady's 110-grain InterBond and 46.3 grains of Reloder-19 yielded .74-inch groups and a 2,824 fps average.

Moving up in bullet weight leads to the 115- and 117-grain spitzer boattails from Nosler, Hornady and Sierra, and each excelled with the selected handload. A top pick would be the 115-grain Ballistic Tip over 37.2 grains of Varget. The velocity of this load is a modest 2,679 fps, but groups averaged .71 inch.

The 120-grain, controlled-expansion bullets are for larger game. Nosler's 120-grain Partition zipped along at 2,771 fps with 43.0 grains of Reloder 17. The 120-grain Speer Grand Slam, in front of 44.1 grains of H-4350, clocked over 2,700 fps and groups were under an inch. Speer's 120-grain Hot-Cor continues to carry its share of the load. With 39.3 grains of Ball-C (2), it cruised at 2,642 fps and punched 1 ½-inch groups.

.25 WSSM handload
Olympic Arms' K8-MAG proved reliable and accurate. This .25 WSSM handload OAL fit the AR's magazine perfectly.

Time will tell if the .25 WSSM will win the hearts of American shooters. But one thing's clear. With the proper loads, the .25 WSSM can hold its own in power, accuracy and reliability in an AR.

Current Magazine Cover

Enjoy articles like this?

Subscribe to the magazine.

Get access to everything Guns & Ammo has to offer.
Subscribe to the Magazine

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

Surefire XSC Micro-Compact Pistol Light: First Look

Surefire XSC Micro-Compact Pistol Light: First Look

Small, lightweight and purpose-built for sub-compact carry guns, Surefire's XSC pistol light takes on EDC illumination segment.

First Look: Springfield Armory Model 2020 Waypoint Bolt-Action Rifle

First Look: Springfield Armory Model 2020 Waypoint Bolt-Action Rifle

At the heart of the rifle is the Model 2020 action which wish designed and built with very tight tolerances thanks to Springfield's technology-driven manufacturing capabilities The stainless steel action features an integral recoil lug, and pairs with a fluted bolt employing dual cocking cams and an enhanced extractor for high pressure loads. The blueprinted and precisely machined action allows Springfield to offer the Model 2020 with .75" MOA accuracy guarantee. Despite being a production rifle, the Model 2020 should rival more expensive custom builds.

Guns & Ammo TV: Cameras Don

Guns & Ammo TV: Cameras Don't Lie: 9mm vs .45 ACP

The age-old question, 9mm vs .45 ACP. For some, this has been asked and answered already. For others, the debate goes on. In this segment of “Cameras Don't Lie,” competitive shooters Patrick Sweeney and Jim Tarr head to the range to put the vaunted loads on record, and then consider the footage.

Air Gun Reviews: Why Shoot Airsoft?

Air Gun Reviews: Why Shoot Airsoft?

In this Guns & Ammo TV segment, Gun Tech Editor Richard Nance and Pro-Shooter Jim Tarr discuss the benefits of airsoft training for uniformed professionals and armed citizens alike.

See More Popular Videos

Trending Articles

Some guns are easier to work with than others, but the Ruger American Rifle doesn't require an engineering degree to tinker with; here's a look at some upgrade options to take your Ruger American to the next level, and make it something a bit different.Top Ruger American Rifle Upgrades Accessories

Top Ruger American Rifle Upgrades

Philip Massaro - March 15, 2018

Some guns are easier to work with than others, but the Ruger American Rifle doesn't require an...

Savage introduces a must-shoot straight-pull rifle: the Impulse.Savage Arms Impulse Rifle - First Look Rifles

Savage Arms Impulse Rifle - First Look

Joe Kurtenbach - January 05, 2021

Savage introduces a must-shoot straight-pull rifle: the Impulse.

Small, lightweight and purpose-built for sub-compact carry guns, Surefire's XSC pistol light takes on EDC illumination segment.Surefire XSC Micro-Compact Pistol Light: First Look Tactical

Surefire XSC Micro-Compact Pistol Light: First Look

Jeremy Stafford - September 10, 2020

Small, lightweight and purpose-built for sub-compact carry guns, Surefire's XSC pistol light...

The first in this new family of Springfield Armory rifles is the Model 2020 Waypoint, the result of years of engineering, testing and evaluation, combined with premium grade components found on rifles costing thousands of dollars more.First Look: Springfield Armory Model 2020 Waypoint Bolt-Action Rifle Rifles

First Look: Springfield Armory Model 2020 Waypoint Bolt-Action Rifle

Guns & Ammo Staff - September 29, 2020

The first in this new family of Springfield Armory rifles is the Model 2020 Waypoint, the...

See More Trending Articles

More Reloading

RCBS announced the new Rebel Single Stage Press is now available and shipping to retail partners.RCBS Rebel Single Stage Press – First Look Reloading

RCBS Rebel Single Stage Press – First Look

Guns & Ammo Staff - July 24, 2020

RCBS announced the new Rebel Single Stage Press is now available and shipping to retail...

The .224 Valkyrie was created to provide optimal long-range performance, and matching factory-load ballistics with handloads is relatively easy..224 Valkyrie Reloading Tips

.224 Valkyrie Reloading Tips

Lane Pearce - January 29, 2019

The .224 Valkyrie was created to provide optimal long-range performance, and matching...

Factory ammunition has never better, but there's always room for improvement. With a small investment of some inspection equipment and time, it's possible for shooters to significantly improve performance of both handloaded and factory ammo. Here's what you'll need and how it's done.How to Shoot Better: Tools and Tips to Improve Factory Ammo Accuracy Reloading

How to Shoot Better: Tools and Tips to Improve Factory Ammo Accuracy

Dave Emary - October 13, 2020

Factory ammunition has never better, but there's always room for improvement. With a small...

There are many reasons for reloading for your handguns. If you currently reload for rifle cartridges, you have almost everything you need except for a die set to load your own handgun ammunition. As with rifle cartridges, reloading for your handgun allows you to tune your loads to your gun, reduce recoil and develop loads that feature the exact brand and type of bullet you want to shoot or hunt with.Handgun Reloads Reloading

Handgun Reloads

Dave Emary - August 27, 2020

There are many reasons for reloading for your handguns. If you currently reload for rifle...

See More Reloading

Magazine Cover

GET THE MAGAZINE Subscribe & Save

Digital Now Included!

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE Arrow

Buy Digital Single Issues

Don't miss an issue.
Buy single digital issue for your phone or tablet.

Buy Single Digital Issue on the Guns & Ammo App

Other Magazines

See All Other Magazines

Special Interest Magazines

See All Special Interest Magazines

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Phone Icon

Get Digital Access.

All Guns and Ammo subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

To get started, click the link below to visit mymagnow.com and learn how to access your digital magazine.

Get Digital Access

Not a Subscriber?
Subscribe Now