A little pistol with a solid pedigree, the new FN 503 9mm sub-compact lived up to its family name in testing and is a solid everyday carry gun. 

Introduced in early 2020, the striker-fired polymer-framed FN 503 borrows the design, performance, and reliability standards of the company’s rugged FN 509 series. FN just folded it into a downsized single-stack package. The result is slim and trim. It holds down the title as the company’s smallest handgun, beating out the legacy FN-S Compact and FN 509 Compact.

Related: Comparing and Breaking Down the FN 503

Addressing the elephant in the room, it compares well to the Glock 43. In fact, it is just slightly shorter. They share the same standard magazine capacity, but the FN-made gun comes with steel rather than plastic sights. 

Glock's single-stack 9mm runs 6.26 inches overall due to a 3.41-inch barrel. However, the G43 is a hair shorter than the FN 503, which stands 4.25 inches tall with a flush-fit 6-shot mag inserted. 
FN 503's included extended 8-shot mag with a grip sleeve adds about an inch to the height. It is an apples-to-apples comparison to the G43 with aftermarket tactical mag extensions. Gratefully, FN ships the 503 with one magazine of each length. 

Our test FN 503 hit the scales at 23.5 ounces with a loaded chamber and a similarly topped-off 6-round mag inserted. It was 25.2 ounces with the longer 8+1 set up.

On the Range

Reliability was impressive on the FN 503. Running a variety of loads from Federal, IMI, PMC, Winchester, and Wolf, we clocked just over 1,000 rounds through the short-framed gun. Our ammunition ranged between 115 and 147 grains and included both range and personal protection loads. The majority of that ammo, about 75 percent, was American Eagle red box FMJs. We logged one jam during testing – ironically on the second round fired  but feel it was due to an improperly inserted magazine. 

Related: Thoughts on the FN 503 After the First 500 Rounds

The FN 503 has a steel trigger with a safety lever inset. It has what is billed by the company as a 5-to-7-pound trigger. We found ours breaks at an average of 5.2 pounds, which is nice for a factory striker-fired trigger pack. 

We had an experienced 12-year-old junior shooter put about 200 rounds through the FN 503 using the shorter mag and he had no problems. The full-length steel chassis lends to less “flex” in the firing cycle than pistols with shorter rail inserts. 

Despite its short barrel, the gun shot relatively flat and proved capable of keeping on center mass out to 25 yards with no issues. At 15 yards, 8-inch action pistol plates were on the menu even with a sight radius shorter than the length of a Twinkie. 


First fielding the test gun in May, we have carried the FN 503 often since then. We probably clocked in nearly 300 hours with the pistol. We started with some repurposed holsters at first but were able to upgrade to purpose-built leather gear from DeSantis Gunhide. This included one of their Inside Heat models for IWB and a Mini Scabbard for OWB

The weight and size profile of the FN 503 unsurprisingly reminds us of the G43 while carrying. The pistol provides just enough heft on the belt to remind you that it is there without dragging you off course as you walk or printing excessively. 

In the end

The FN 503 performed well and met expectations when it came to reliability and durability. It is intended as a discreet EDC that brings more to the party than a .380 or .32 ACP-chambered cricket, and it carries well. While having more rounds on tap than your typical snub-nosed revolver  and with a faster reload  it squares with guns like the Glock 43 and S&W M&P Shield 9 in capacity and intended use. 

About the worst brick we can throw at it is that the latest generation of micro-compact 9mm pistols, such as the Sig Sauer P365 and Springfield Armory Hellcat, surpass the FN 503 in the ammo capacity department. Further, competitors like the G43 have a ton of aftermarket upgrades floating around while the FN is more neglected. 

Still, the gun checks a lot of boxes and is an easy call for someone looking for a dependable carry gun without a lot of frills. That is especially if they are already FN fans. However, even if they aren't already fans, they likely will be after picking up one of these. 


Read More On:
revolver barrel loading graphic