.356 TSW

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A cartridge comparison between the 9mm Luger (left), .356 TSW (middle) and .357 SIG (right). Image sourced from GUNS Magazine.

The .356 TSW (.356 Team Smith & Wesson) is a centerfire handgun cartridge that was designed by Smith & Wesson in 1994, and released commercially in 1995. The .356 TSW is very similar in size to a 9mm Luger, or a 9x21mm. It was designed to be used in IPSC shooting events, but rule changes addressing the use of the new cartridge made it obsolete almost immediately. Smith & Wesson would briefly attempt to re-market the cartridge as the .356 Tactical Smith & Wesson, but this flopped as well, and factory loads appeared to have no real advantage over traditional 9mm ammo. As a result, it mostly became an obscurity.

Ammunition appears to still be made (as of early 2021) by CorBon and Underwood, who were both convinced by Scott Sullivan around 2016-2017 to begin production again on the cartridge. According to Massad Ayoob's article on the .356 TSW at GUNS Magazine, both manufacturers are using casings manufactured by Starline Brass. Conversion kits for Glock 19 Gen 3 and 4 models were available, but it's unclear if that's still the case.

Design & Origins

The .356 Team Smith & Wesson cartridge appears to have been largely developed for Major power IPSC competition. Essentially it allowed for the higher capacity of a 9mm handgun, while qualifying among more powerful higher-caliber handguns, offering a competitive advantage, mostly in magazine capacity. From Frank Barnes' Cartridges of the World, 14th Edition:

"The centerfire pistol cartridge was designed by Smith & Wesson in 1994 as an IPSC round. The .356 TSW fit in a 9mm magazine, and S&W convinced Federal to load it and submit it for SAAMI-spec approval, where it saw promise as a Limited-class competition round. However, because of a rules change, USPSA didn’t approve it for that class, and there were other rounds that were better choices for Open guns. S&W scrapped the project, effectively killing the .356 TSW. Federal case heads and the box were marked “356 TSW.” The load was a 147-grain FMJ Match product number GM356SW."

Additional comments by Frank Barnes:

"The TSW is simply a slightly longer 9mm case (9x21.5mm), and it uses ordinary 9mm bullets for reloading purposes. To meet IPSC’s major power factor back then, the TSW had to send a 124-grain 9mm bullet at about 1,450 fps. A .356 TSW performs on par with hot 9x21 IPSC loads or full-house .357 SIG loads, but it has an advantage over the .357 SIG. The SIG cartridge is a bottleneck round, a .40 S&W casing necked down to 9mm. The .356 TSW is a straight walled 9mm casing, thus, more .356 rounds can fit into a magazine. The .356 TSW was mainly chambered in 150 Smith & Wesson Model 3566 Performance Center .356 TSW pistols."

Ballistic Performance

Below is ballistic performance information for various .356 TSW loadings. The first two (Federal and Winchester) loadings are sourced from Cartridges of the World, 14th Edition.

Bullet (Weight / Type) Powder Grains Velocity Energy Source / Comments
Federal 147 Gr Match FMJ FL ? 1,220 fps 486 ft lbs Federal GM356SW
Winchester 124 Gr FMJ VV-3N37 9.1 Gr 1,446 576 ft lbs IPSC Loads List 2001
Underwood 115 Gr Sporting JHP N/A N/A 1,600 654 ft lbs N/A
Underwood 124 Gr Sporting JHP N/A N/A 1,450 579 ft lbs N/A
CorBon 115 Gr JHP N/A N/A 1,600 650 ft lbs N/A


  • Bullet diameter: .355 in (9.0 mm)
  • Neck diameter: .380 in (9.7 mm)
  • Shoulder diameter: .3804 in (9.66 mm)
  • Base diameter: .3907 in (9.92 mm)
  • Rim diameter: .394 in (10.0 mm)
  • Case length: .850 in (21.6 mm)
  • Overall length: 1.160 in (29.5 mm)
  • Rifling twist: 1-10"

Ammunition Availability

Despite mostly being an obscurity, it appears that a number of ammunition manufacturers still produce .356 TSW ammo. Including:

Other Resources

".356 Team Smith & Wesson" SAAMI Specs (Archived) - Official SAAMI specs for the .356 TSW cartridge, archived on WayBackMachine.

.356 TSW (by Wiley Clapp) - A very brief article from American Rifleman, written by Wiley Clapp, discussing the .356 Team Smith & Wesson cartridge.

The .356 TSW: Promising Cartridge Back from the Dead - An article by Massad Ayoob at GUNS Magazine. Discusses in-depth the revival of this formerly dead cartridge.

Video Explanation

An excellent video by Ian McCollum of Forgotten Weapons, on the Smith & Wesson Model 3566 and the .356 TSW cartridge it fired.