5.7x28mm vs 22 WMR: The PDW Caliber Comparison
How the 5.7x28mm PDW Concept Was Born
In the early 1990s, NATO issued a challenge to arms manufacturers: design a personal defense weapon that could defeat body armor at close range while keeping the platform light and compact. FN Herstal answered with the P90 submachine gun and a brand-new cartridge built specifically around that mission – the 5.7x28mm. The round was engineered from scratch to push a small, lightweight bullet at extremely high velocity, giving it armor-defeating potential that nothing else in a handgun-sized package could match at the time.
The civilian version of this concept arrived with the FN Five-seveN pistol, and later with semi-auto carbines like the PS90. Most civilian 5.7x28mm ammunition is not armor-piercing – that’s restricted to military and law enforcement – but the underlying ballistics still make it a genuinely interesting cartridge. Whether you’re a range shooter, a varmint hunter, or someone curious about PDW-style platforms, understanding where this round came from helps explain why it performs the way it does.
Core Ballistics – Velocity, Weight, and Energy
The Numbers Side by Side
| Cartridge | Bullet Weight | Muzzle Velocity | Muzzle Energy |
|---|---|---|---|
| 5.7x28mm (SS197SR) | 40 gr | ~1,650 fps | ~242 ft-lbs |
| 22 WMR (standard) | 40 gr | ~1,875 fps (rifle) / ~1,450 fps (pistol) | ~310 ft-lbs (rifle) |
| 22 WMR (30 gr) | 30 gr | ~2,200 fps (rifle) | ~320 ft-lbs (rifle) |
The 5.7x28mm fires a 40-grain bullet at around 1,650 fps from a pistol-length barrel. That’s genuinely fast for a handgun cartridge. The 22 WMR can actually match or beat that velocity from a rifle barrel, but drops noticeably from a short pistol barrel – often falling to the 1,200-1,450 fps range depending on barrel length.
What separates the two is consistency and platform design. The 5.7x28mm was optimized for short barrels – it was designed to perform from a 4.8-inch handgun barrel and still deliver meaningful velocity. The 22 WMR is a rimfire cartridge originally designed for rifles, and it loses a significant chunk of performance when stuffed into a compact handgun. If you’re shooting a carbine with either round, the gap narrows considerably.
Where 22 WMR Holds a Real Advantage
Cost and Simplicity
The 22 WMR’s biggest edge is cost. A box of 50 rounds of 22 WMR typically runs $12-$20 depending on brand and region. Comparable 5.7x28mm ammunition often costs $25-$45 for the same count. Over a year of regular range shooting, that difference adds up fast – sometimes into the hundreds of dollars.
The platform variety also favors 22 WMR. You can find revolvers, bolt-action rifles, lever guns, and semi-automatic pistols chambered in 22 WMR from dozens of manufacturers at a wide range of price points. A shooter on a budget can get into a quality 22 WMR platform for $300-$500. A quality 5.7x28mm pistol starts around $900 and goes up. If affordability matters – and for most people it does – 22 WMR is the practical choice.
Head-to-Head Trajectory and Terminal Performance
Trajectory
Both cartridges are relatively flat-shooting compared to heavier pistol rounds. The 5.7x28mm holds a slight edge in trajectory consistency from short barrels because it was optimized for that environment. From a rifle or carbine, 22 WMR becomes competitive and can even outperform in raw energy numbers with lighter bullet loadings.
Terminal Performance
This is where both cartridges face honest criticism. Neither the 5.7x28mm nor the 22 WMR is considered a top-tier self-defense round by most ballistic experts. The 5.7x28mm offers better penetration – typically 12-16 inches in gelatin with quality JHP loads – which meets FBI minimum standards. The 22 WMR often falls short of that standard, especially from pistol barrels, with some loads producing inconsistent expansion.
For varmint hunting, 22 WMR is a proven performer out to 100-125 yards on small animals. The 5.7x28mm can do similar work, but the ammo cost makes it harder to justify for high-volume varminting. For range use, both are enjoyable low-recoil options that are easy to shoot well.
Best Pistols and Carbines for Each Caliber
5.7x28mm Platforms
- FN Five-seveN – the original, still the benchmark; 20-round magazine, excellent ergonomics
- Ruger-57 – more affordable entry point, 20-round capacity, widely available
- FN PS90 – semi-auto carbine, 50-round magazine, compact bullpup design
- CMMG Banshee – AR-style pistol/carbine option for those who want familiar controls
22 WMR Platforms
- Kel-Tec PMR-30 – semi-auto pistol with 30-round capacity, lightweight, fun range gun
- Ruger LCR – compact revolver option for carry-minded shooters
- Savage A22 Magnum – semi-auto rifle with solid accuracy at a reasonable price
- Ruger Super Blackhawk – single-action revolver for those who want a classic feel
If you’re shopping for a 5.7x28mm platform, look for features like aftermarket magazine availability, a solid warranty, and reliable extractor performance – the rimless case design makes extraction generally consistent, but not all manufacturers execute it equally well. For 22 WMR, prioritize barrel length relative to your use case – a short barrel will cost you meaningful velocity.
Common Mistakes When Choosing Between These Two
Shooters often stumble when picking between these calibers for the wrong reasons. Here are the most common errors:
- Assuming 5.7x28mm is a military-grade armor-piercing round in civilian form – civilian loads are standard JHP or FMJ, not AP
- Buying a 22 WMR pistol expecting rifle-level performance – short barrels kill velocity; test your specific load in your specific barrel
- Overlooking ammo availability before buying the gun – 5.7x28mm can be hard to find locally in many parts of the US and Canada
- Choosing based on magazine capacity alone – a 30-round PMR-30 is impressive on paper, but reliability matters more than round count
- Ignoring platform costs – 5.7x28mm pistols cost significantly more upfront, and that gap doesn’t disappear
- Using either round as a primary home defense caliber without testing penetration from your specific barrel – always verify performance in your actual firearm
- Dismissing 22 WMR as a “lesser” round – for varminting and range use, it’s genuinely capable and economical
Ammo Cost and Availability – A Practical Check
Quick Checklist Before You Buy
Before committing to either caliber, run through this checklist:
- Can you find ammunition at local gun stores in your area, not just online?
- What is the per-round cost for your primary use – range, hunting, or defense?
- Are there at least 3-4 different load options available for your intended purpose?
- Is the platform you want reliably in stock, or is it a limited-availability item?
- Do you have a local range that allows the caliber? (Some indoor ranges restrict high-velocity small-caliber rounds)
- Can you afford to practice regularly at current ammo prices?
- Is there a reliable supply chain for this caliber in Canada if that’s your market?
5.7x28mm ammo is available online without much trouble in the US, but shelf availability at local stores is inconsistent. In Canada, it’s even more limited and more expensive. 22 WMR is widely stocked at sporting goods stores, big-box retailers, and gun shops across both countries – it’s a practical advantage that matters if you shoot regularly.
FAQ – Is the 5.7x28mm Worth It Over 22 WMR
Quick Takeaways
- 5.7x28mm is faster from short barrels and more consistent in terminal performance
- 22 WMR is cheaper, more widely available, and offered in more platform types
- Neither caliber is a top-tier defensive round, but 5.7x28mm clears the FBI penetration standard more reliably
- 22 WMR wins for varmint hunting on a budget
- 5.7x28mm wins for PDW-style use and high-capacity semi-auto platforms
- Your local ammo supply should be a deciding factor, not just ballistic data
Q: Is 5.7x28mm actually better than 22 WMR ballistically?
A: From short pistol barrels, yes – the 5.7x28mm was engineered for that environment and delivers more consistent velocity. From a rifle barrel, 22 WMR can match or exceed it in raw energy. Context matters.
Q: Can I use 22 WMR for self-defense?
A: It’s not the first choice most instructors would recommend, especially from a short barrel. Penetration can be inconsistent. If 22 WMR is what you have, quality JHP loads from a longer barrel are a better bet than FMJ from a snub-nosed revolver.
Q: Why is 5.7x28mm so expensive?
A: It’s a lower-volume cartridge with fewer manufacturers producing it. FN dominated the market for years, and while competition has increased, it hasn’t driven prices down to rimfire levels. Expect to pay roughly 2-3 times the per-round cost of 22 WMR.
Q: Is the FN Five-seveN worth the price?
A: If the platform and caliber fit your specific needs – PDW-style shooting, high capacity, low recoil – it’s a well-built pistol with a strong track record. If you’re buying it mostly because it looks cool, the price premium is hard to justify over a more versatile handgun.
Q: Which is better for varmint hunting?
A: 22 WMR is the practical winner here. It’s proven at 100+ yards on small animals, ammo is affordable enough for high-volume use, and platform options are plentiful. 5.7x28mm can do the job but costs more per trigger pull.
Q: Is 5.7x28mm legal in Canada?
A: Yes, civilian 5.7x28mm ammunition and firearms are legal in Canada. However, ammo availability is more limited and prices are higher than in the US. Verify local regulations and check supply in your province before purchasing a platform in this caliber.
