The attention of American shooters was seized a few years ago by FN's revolutionary new PS90 carbine and the 5.7x28mm cartridge. The subsequent introduction of the Buck Rogers-esque 5.7 pistol was equally noteworthy.

As much as people talked about FN's new introductions, I must confess that neither of the unusual-looking blasters really blew my skirt up. To be frank, I wasn't too excited about those tiny 28- and 40-grain projectiles for self-defense either. But a few positive reports about the cartridge's performance and chance encounters with friends' PS90 carbines and Five-seveN pistols made me take a closer look at FN's diminutive duo.

The PS90 Carbine
FN's P90 submachine gun and 5.7x28mm round were developed in 1986-1987, though it took more than a decade to go from concept to production for the civilian market. The P90 was designed as a Personal Defense Weapon (PDW). FN's P90 found favor with soldiers who operate in tight spaces like vehicles and aircraft. In that role, it is a very practical piece. But collectors don't give a lick about practical; they dig the P90's looks and revolutionary new features. FN introduced the civilian-legal version, dubbed the PS90, to satisfy that demand.

The semiautomatic PS90 is a straight blowback design with an integral optic. Because it is a conventional blowback design, the bolt group is quite substantial. The bolt reciprocates against a pair of springs that surround a pair of steel guide rods, which fit into recesses in the barrel-support group for smooth, solid operation. The 161⁄16-inch barrel is hammer-forged and chrome-lined, and it has a muzzle brake with six ports.

One of the PS90's most noteworthy features is its unique, horizontally mounted, polymer magazine that sits above the barrel, parallel to the bore axis. Its position necessitates an unusual magazine design that stores cartridges perpendicular to the bore.

The rounds are loaded conventionally, but inserting the second round rotates the first cartridge clockwise approximately 80 degrees within a spiral chute. The third round moves the first round to a 90-degree angle to the bore axis, and subsequent rounds make their way into a staggered-column configuration. The loaded magazine is slid into the receiver/barrel-support group from the rear and is locked into the magazine opening with moderate downward pressure.

As the bolt's forward movement strips a round, the next cartridge instantaneously twists around the chute and into position. The last two "rounds" are actually nylon rollers that can be removed only while disassembling the magazine. An internal block reduces the capacity of the PS90 magazine to 30 rounds instead of 50 as in the P90.

One safety note on the PS90: Remove the magazine before operating the charging handle to clear and safe the gun because the magazine makes it impossible to see the breech. The ambidextrous magazine release is on top of the buttstock.

An integral optic was mounted atop the receiver/barrel-support group of the PS90 USG that I received. It is a zero-magnification reflex unit intended for fast, close-in work. Its reticle has a circle with a dot in it and three black posts that glow red in low light thanks to a little tritium. The reflex sight of the USG can be removed and replaced with an adaptor for use with other optics. The PS90 TR (Triple Rail) is available with a Picatinny rail instead of the standard reflex sight.

The cocking handle is a low-profile, ambidextrous affair that is easy to manipulate. The bolt does not stay open after the last shot.

Even though it is a bullpup, I was pleased to see the PS90's trigger pull come in at a respectable 7 pounds, 10 ounces, with minimal mushiness. The rotating safety is mounted just below the trigger.