A closer look at the FN PS90 5.7x28mm

The magazine uses a mechanism to turn the rounds 90 degrees in order to feed them into the chamber. Standard capacity for the magazine is 50 rounds but it comes with a 30 rounder with a spacer to keep it from going over 30. This can easily be cut in order to modify the magazine to accept the standard 50 rounds.

A closer look at the bottom

As you can see, the cartridge makes a turn as you push another one into the magazine

Another view

The firearm can be easily taken down with the press of a button into 4 main parts. The upper receiver, the bolt, the trigger assembly, and the main plastic shell which holds it all.

The trigger group is almost entirely made of plastic. Including the hammer and sear. The only thing that is not plastic are the springs as far as I could tell. It’s VERY lightweight.

As you can see, after you remove the upper receiver and pull the bolt out you can then slide the butt plate off in order to access the trigger group. It slides out with the pull of a tab.

The bolt group

You can see in this picture the button that needs to be pressed in order to take the firearm down. It’s extremely simple.

A view of the open chamber

I modified the spacer in the 30 round magazine in order to accommodate the standard 50 round capacity. So far there have been no malfunctions. The 50 round capacity and small size of the firearm make for an excellent home defense carbine.

The empty casings drop out of the bottom here instead of ejecting to the side like your standard firearm. Flip-flop & sandle wearers beware! My fiancée burned her foot on an empty casing while shooting it.

A size comparison to other firearms. As you can see, the PS90 is very compact. Even without an SBR conversion. (from left to right: S&W M&P Shield, S&W M&P9 pro series CORE, S&W 625 PC, S&W 1911, Barnes Percision Match carbine with Vortex Razor HD Jerry Miculek 1-6)

A cartridge comparison. (From left to right: 9mm, .45 ACP, 5.7×28, .223, 50 BMG A-MAX)