The KelTec PR57 is one of the more innovative pistols seen at the 2025 Shot Show.  As indicated by the name, the pistol is chambered in 5.7×28. The pistol is top-loaded with a 20-round magazine. The magazine is integral, like a Steyr 1912 or a C96 broom handle Mauser. This allows for a smaller grip, fewer parts, and a very thin and light pistol. As expected, there is a significant muzzle flash and blast when the pistol is fired. Recoil is more than most .22 rimfire pistols but less than most 9mm pistols.  The capacity is listed as 20+1. How is the 21st round loaded?

 

The 20-round internal magazine is actually a 21-round magazine. To “top off” the pistol with an additional round, push the 21st round into the magazine. When the slide is released, it will strip the 21st round into the chamber, and you will have 20 rounds in the magazine with one in the chamber.

Bottleneck cartridges make for reliable feeding.  Because the magazine is integral, the feed lips are subject to less possibility of damage. No tolerance is needed to accommodate slight differences in removable magazine manufacture. The integral feed lips are sturdy and unlikely to be easily damaged. Stripper clips are much easier and cheaper to manufacture than magazines.

Using stripper clips to reload is much slower than using a detachable magazine. A stripper clip reload is as fast as reloading a revolver with speed loaders. Twenty or 21 rounds of ammunition is likely to allow an opportunity to reload at some point. Twenty rounds of ammunition would require three reloads in a six-shot revolver.

Fully loaded, the KelTec PR57 weighs 19 ounces, four ounces less than an unloaded Glock 19. The pistol is less than 1 inch thick, about the same height as a Glock 19, and a little shorter than the Glock 19.

The disassembly procedure for the pistol is simple. Push the trigger forward. Pull the slide off the front of the frame. The slide and barrel are locked together. You now have the slide assembly and the frame.  It appears cartridges could be removed from the magazine by simply pushing them forward, free from the magazine feed lips.
 

KelTec PR57 Rotary Barrel 5.7x28mm Pistol

 
The KelTec PR57 uses a patented rotating front locking mechanism. A lug on the back of the barrel fits into a slot on a part called the trunion by KelTec. The trunion fits between the barrel and the frame.  As the barrel and slide move backward in recoil, the lug on the barrel is rotated by the trunion and unlocks. The slide continues backward, ejecting the cartridge case.
 

The trunion is shown in between the slide and the frame. It is a relatively small part, easily manufactured.

  
How do you unload the magazine on the PR57? There are three ways to do so.

1. You can work the slide back and forth, ejecting a round with each slide cycle until the magazine is empty.
2. You remove the slide from the frame. This is extremely simple on the PR57. Push the trigger forward. Pull the slide forward, off the frame. Then you can push each cartridge forward, out of the magazine feed lips, until the magazine is empty.
3. You can remove the magazine floor plate and the base plate pin at the rear of the grip. The magazine spring will be under pressure, so the base plate must be controlled to keep the baseplate, spring, and cartridges from flying out of the pistol. It is recommended that a punch be used to remove the pin.