5.7x28mm vs. 4.6x30mm: Why the U.S. Secret Service Chose FN’s High-Velocity PDW Round

Why the 5.7x28mm Was on the Table for the U.S. Secret Service

The U.S. Secret Service is tasked with a highly specialized mission profile: protect high-value individuals in complex, often unpredictable environments—everything from crowded political events to high-speed motorcades. These scenarios demand lightweight, compact weapon systems that can deliver rapid, accurate fire and defeat threats wearing soft body armor.

During internal evaluations in the early 2000s, the Secret Service determined that traditional sidearms and submachine guns (like those chambered in 9mm or .45 ACP) lacked the penetration capability and control needed for dynamic protective operations. This led them to assess a newer class of Personal Defense Weapons (PDWs).

The 5.7x28mm cartridge, developed by FN Herstal, was seen as a compelling solution—offering high magazine capacity, exceptional velocity, armor-penetrating potential, and compatibility with both pistol and compact carbine platforms. This capability suite made it a perfect match for executive protection needs, especially in tight quarters or vehicular engagements.

Ultimately, the Secret Service adopted both the FN P90 and FN Five-seveN, officially making 5.7x28mm part of its protective toolkit.

What Makes the 5.7x28mm Stand Out?

Velocity and Terminal Behavior

The 5.7x28mm launches lightweight projectiles (typically 27 to 40 grains) at 2,000–2,800 feet per second, depending on barrel length. The round was specifically engineered to defeat soft body armor (NIJ Level IIIA) with dedicated military loads (e.g., SS190).

Unlike traditional pistol rounds, which rely on mass and expansion for terminal effect, 5.7x28mm uses velocity-driven penetration and fragmentation, often yawing or tumbling in tissue for improved wounding.

Low Recoil and High Control

Recoil energy for 5.7x28mm is roughly 30–40% less than 9mm, allowing for fast, accurate follow-up shots. This is a critical factor when agents may need to fire in confined spaces like vehicles, airplanes, or hallways, where overpenetration and recoil control are major concerns.

High Capacity and Modularity

• FN Five-seveN Pistol: 20+1 capacity, full-size pistol platform
  
  
• FN P90 PDW: 50-round magazine in a top-mounted configuration; ambidextrous bullpup design

This modularity enables protective agents to use the same cartridge in both handgun and carbine, streamlining training, logistics, and mission deployment.

Lightweight Loadout

A fully loaded FN Five-seveN weighs significantly less than a similarly equipped 9mm or .45 pistol. Similarly, the P90 with 50 rounds of 5.7 weighs less than many 30-round AR-platform rifles—an essential factor in long security details or mobile assignments.

The European Challenger: 4.6x30mm by Heckler & Koch

Background and Intent

Around the same time FN developed the 5.7x28mm, Heckler & Koch engineered the 4.6x30mm cartridge for similar NATO PDW requirements. The round is used exclusively in the H&K MP7, a compact personal defense weapon designed for elite military and counterterrorism units.

Like the 5.7x28mm, the 4.6x30mm fires small, high-velocity bullets intended to defeat soft body armor and deliver high-capacity performance in a lightweight system.

Ballistics and Purpose

The 4.6x30mm fires 31–40 grain bullets at speeds between 2,300 and 2,600 fps, giving it similar penetration capabilities to the 5.7, especially when paired with armor-piercing loads like the DM11 AP.

It generates less felt recoil than 9mm, and like 5.7, it enables controlled automatic or rapid fire in a very compact weapon.

However, the cartridge is almost exclusively tied to the MP7 platform, with no handgun equivalents or wide-scale adoption in non-military contexts.

Side-by-Side Comparison: 5.7x28mm vs. 4.6x30mm

Feature	5.7x28mm (FN Herstal)	4.6x30mm (Heckler & Koch)
Origin	Belgium (late 1980s)	Germany (late 1990s)
Platform Support	P90 PDW, Five-seveN pistol, others	H&K MP7 only
Velocity	2,000–2,800 fps	2,300–2,600 fps
Bullet Weight	27–40 gr	31–40 gr
Penetration	Effective vs soft armor (SS190)	Effective vs soft armor (DM11 AP)
Recoil Control	Extremely light	Comparable, slightly higher impulse
Magazine Capacity	20–50 rounds (platform-dependent)	20–40 rounds
Civilian Options	Yes (Ruger-57, PSA Rock, LC Carbine)	No civilian support
Adoption	U.S. Secret Service, ICE, other LE	German KSK, SEK, GSG 9, NATO SF

Why the U.S. Chose 5.7x28mm Over 4.6x30mm

1. Broader Platform Ecosystem

5.7x28mm was adopted into both pistol and PDW formats (Five-seveN and P90), allowing cross-platform compatibility and simplifying ammunition logistics. By contrast, 4.6x30mm is locked to the MP7, which, while compact and effective, has no corresponding handgun or training counterpart.

2. Greater Commercial and LE Availability

By the early 2000s, 5.7x28mm platforms were already approved for limited law enforcement and civilian use. This accelerated adoption in U.S. agencies looking for off-the-shelf availability and domestic production. H&K’s tighter restrictions and military-only orientation for the MP7 hindered its U.S. expansion.

3. Training and Ergonomics

The P90 offered ambidextrous operation, intuitive controls, and a uniquely balanced bullpup form, making it highly maneuverable. The Five-seveN mirrored the controls of common service pistols, allowing for easier transition from 9mm sidearms. The MP7's ergonomics are excellent—but less familiar to those outside of European special forces units.

Final Thoughts: Why 5.7x28mm Became the U.S. Choice

The 5.7x28mm cartridge checks multiple mission-critical boxes for agencies like the Secret Service:

• Lightweight, low-recoil ballistics
• Soft armor penetration at close-to-mid range
• Streamlined logistics across handguns and carbines
• Proven reliability and rapid follow-up potential
• Civilian market integration for ongoing training and availability

While the 4.6x30mm MP7 system is extremely capable, its narrow platform support and limited commercial accessibility made 5.7x28mm a more versatile and strategic choice for U.S.-based protective units.

With growing civilian interest, new ammunition development, and more manufacturers supporting the 5.7 ecosystem, it continues to evolve from a niche NATO round to a serious option for law enforcement, private defense, and specialized shooters.

Looking to stock up on 5.7x28mm ammo? Whether you're running a FN Five-seveN, Ruger-57, or PSA Rock, we've got premium loads ready to ship.
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FAQs

Did the U.S. Secret Service adopt both P90 and Five-seveN?

Yes. Both platforms are fielded in specialized roles, particularly among protective details.

Is 5.7x28mm still used today?

Yes. It's in use by the Secret Service, ICE, and other agencies. Its civilian presence is also growing thanks to Ruger, PSA, and CMMG.

Can civilians buy 4.6x30mm ammo or MP7s?

No. The MP7 is a military-grade select-fire weapon, and 4.6 ammo is restricted. There are no civilian rifles or pistols chambered in this caliber.

Which round has better armor penetration?

Both can defeat Level IIIA soft armor. 4.6x30mm tends to penetrate slightly better through harder barriers, but 5.7 offers broader load variety.

Is 5.7x28mm good for self-defense?

With the right ammunition—like Speer Gold Dot or FN SS198LF—it can be extremely effective. Its controllability and capacity make it attractive for PDW use.