Description
The PWA AR57 LEM Gen 2 5.7×28 16″ Fluted Barrel 2-50Rd Magazines is a purpose-built, upper-receiver assembly that converts a standard AR-15 lower into a high-capacity 5.7x28mm carbine. It uses a unique top-mounted magazine system and comes ready to run. I’ve put a few hundred rounds of both FN and American Eagle ammo through one, and it’s a blast—literally and figuratively—offering a different kind of shooting experience from your typical 5.56 AR.
Key Features
- Complete Upper Assembly: Everything you need to convert your AR-15 lower. It’s drop-in ready, with no gunsmithing required.
- Unique Top-Loading Magazine System: Uses modified FN P90 50-round magazines that eject spent brass downward through the magwell.
- 16″ Fluted Barrel: Provides a full legal rifle length while reducing weight and aiding in heat dissipation.
- Included Magazines: Comes with two 50-round magazines right out of the box for immediate high-capacity fun.
- 5.7x28mm Chambering: Low-recoil, high-velocity round that’s flat-shooting and effective for varminting or tactical training.
Specifications & Details
| Specification | Detail |
|---|---|
| Caliber | 5.7x28mm |
| Barrel Length | 16 inches (Fluted) |
| Magazine Capacity | 50 Rounds (x2 included) |
| Compatibility | Standard AR-15/Mil-Spec Lower Receiver |
| Upper Construction | Forged Aluminum |
| Handguard | M-LOK Compatible |
This isn’t just another upper. The heart of the system is that clever top-mounted mag, which changes the entire handling dynamic. You get the familiar ergonomics and trigger of your trusted AR lower—be it an Anderson, Aero Precision, or PSA build—paired with the unique feeding and ejection of the P90 platform. The fluted barrel is a nice touch, keeping the weight down to a manageable level, which you’ll appreciate with those full 50-round mags. At a price of $1073.85, you’re paying for a specialized tool that delivers a specific, high-volume experience.
Who This Is For
This upper is for the shooter who already has a spare AR-15 lower and wants to explore the 5.7x28mm world without buying a whole new dedicated rifle. It’s perfect for varmint control where follow-up shots are key, or for someone who just loves the idea of a 50-round magazine in a lightweight, low-recoil package. It’s also a fantastic training tool for developing shot discipline—because you can burn through ammo very quickly if you’re not careful.
Pros & Cons
Pros: The high capacity is an undeniable thrill and practical advantage. Recoil is negligible, making it easy to stay on target. The fluted barrel looks great and functions well. Since it uses your existing lower, it’s a cost-effective way to add a new caliber to your safe. It’s available at firearms-missouri.com for Missouri residents and nationwide.
Cons: 5.7x28mm ammo, while more available than it used to be, is still pricier than 5.56. The top-mounted mag changes your manual of arms and can interfere with some optic mounts—you’ll need a high-rise or scout-style mount for many red dots. Sourcing extra magazines means finding specific P90 mags or the PWA-modified versions.
Frequently Asked Questions
Q: Does this work with any AR-15 lower?
A: Yes, it’s designed for standard mil-spec AR-15 lowers. I’ve run it on both an Aero Precision and a Palmetto State Armory lower without any issues. Just remember, FFL transfer required for firearm purchases of the lower itself.
Q: Where do the spent brass casings go?
A: This is the cool part. The casings eject downward through your lower receiver’s magwell. You’ll want to make sure that area is clear, and it means you won’t have brass flying to the side, which is a nice perk for left-handed shooters or crowded ranges.
Q: Is the 5.7x28mm round effective for anything beyond target shooting?
A: Absolutely. While it’s a blast on steel, it’s a legitimate varminting and small predator cartridge. With the right loads, it offers very good penetration and flat trajectory out to 150-200 yards, making it excellent for prairie dogs or coyotes. That said, always check your local regulations.
If you’re looking to add a unique, high-capacity option to your existing AR platform, the PWA AR57 Gen 2 upper delivers a seriously fun and functional experience. Check it out on our site.
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