Review: FN 503 Slim-Line 9mm Pistol

Fabrique Nationale has been around a long time and is among the most respected makers in the world.

Handguns, rifles and heavy machineguns are among their products. The military uses many FN products.

The U.S.-made 503 is their entry into the slim-line 9mm subcompact market. They will butt heads with Springfield, GLOCK and others for sales.

It is an even bet FN fans will flock toward the 503 rather than a GLOCK 43 for good reason. But all of us should take a hard look at this credible choice.

While shortages demand we grab what is available, the 503 seems more available than some pistols.

I cannot imagine disappointment with the FN 503. This is a great all-around handgun. 

FN 503 Features

The pistol shares features with the full-size 509. The striker and trigger are similar.

The 503 features three passive safeties, and like most modern striker fired pistols, it doesn’t have a manual safety.

These safeties are the striker block, a lever set in the trigger to prevent lateral discharge, and the trigger disconnect.

There is a visual loaded chamber indicator. The extractor, ejector and internal parts are service-grade, intended for hard use. 

An advantage of a pistol like the 503, is that the maker did not have to develop nitrocarburizing technology or ship the gun out to be plated or finished.

FN uses the corrosion-resistant finish on military guns and the 503 as well. Another advantage is that the 503 is a modular platform.

At some point, grip/frame assemblies will allow changing the internals to a larger frame.

I guess that is a cool thing, but I think this modular design is a greater aid for institutional use than for individuals.

Just the same, it is nice to have and it makes maintenance very easy.  

FN 503 Specifications

• Type: Striker-Fired, Recoil-Operated, Semi-Automatic
• Cartridge: 9mm Luger
• Capacity: 6+1 rds., 8+1 rds.
• Barrel: 3.1 in.
• Overall Length: 5.9 in.
• Weight: 21 oz. 
• Width: 1 in.
• Height: 4.4 in.
• Finish: Black Nitride 

The pistols dimensions are just right for concealed carry. The slide is about 0.9 inches wide. The grip is about 0.01-inch narrower.

The barrel is 3.1 inches long. Overall length is 5.9 inches. This is a neat, almost svelte, package for concealment.

The pistol is similar to size to other compact pistols. Worn in a proper holster, the FN conceals as readily as any slim-line 9mm pistol.

The decision comes down to features and shootability, not to mention value for your hard-earned dollar. The pistol features all-steel sights.

They are snag-free and offer a good sight picture. I believe that small guns need good sights and a good trigger.

You are limited by a short sight radius and pressing a trigger against a light pistol is a more difficult task than firing a larger handgun well.

The FN 503 has good sights and the trigger proved useful as well. The trigger breaks clean and is consistent.

Trigger compression is five pounds even. 

Feel and Other Features

The pistol does not have a manual safety or takedown lever. The slide lock and magazine release are the only controls.

The slide stop is removed for takedown, then replaced after fieldstripping.

Remember to press the little retaining wire in the slide-stop aperture back into place if it moves. This is a neat system.

Once fieldstripped, the pistol exhibited excellent fit and finish with no tooling marks and good polish.

The grip stabilizes the hand as we operate the action, it is a pathway to trigger control.

The grip texture is ideal for most of us, with a good balance of adhesion and abrasion. You do not want a small gun to slip and squirm during recoil.

The FN 503 is an excellent design in this regard. The pistol is supplied with a six-round flush-fit and an eight-round extended magazine.

The 503 is easier to shoot well with the extended magazine, but not by a huge margin.

As for which magazine to utilize in concealed carry, it depends on whether you need that nth degree of concealment.

Performance and Load Testing

During testing, I fired a wide variety of loads. I began with the Remington UMC FMJ load and then the Federal Syntech loading.

The pistol did not squirm, but recoiled straight back. Accuracy was good, as I drew and fired at man-sized silhouette targets at five, seven and 10 yards.

I was punching the X-ring in short order. I also fired the Winchester Silvertip, a proven defense loading.

Reliability is good. I moved to the 15-yard line and fired two Hornady loads from a standing braced barricade.

First was the Hornady 115-grain Extreme Terminal Performance (XTP) and then the American Gunner 124-grain XTP +P.

I wanted to test at least one +P load. Five shots from each load went into a tight 2.5-inch group — excellent for this type of handgun.

Firing slowly from a braced position isn’t combat shooting, but confirms sight regulation and accuracy potential.

You knew you fired a +P loading with the American Gunner, but recoil was controllable. Ball, JHP and +P loads proved well-suited for use with FN 503. 

Conclusion: FN 503 Review

I like the FN 503 a lot.

Many years ago, I turned a Chief’s Special .38 and later a Star PD .45 a nice copper/brown carrying them concealed in the humid summer under a shirt.

The FN 503’s black nitride coating would eliminate this concern. The pistol is much easier to use than either of these.

The FN 503 9mm makes the grade. 

What do you think of the FN 503? Let us know in the comments section below!