Is the threaded muzzle compatible with 5.56mm muzzle devices?

No, it is not directly compatible. The muzzle is threaded 1/2-28, which is the same thread pattern as many .22 caliber and 5.56mm devices, but the bore diameter is for the smaller 5.7x28mm projectile (.224" vs .224"). You must use muzzle devices specifically rated and bored for 5.7x28mm to avoid a baffle or end cap strike, which constitutes a catastrophic failure.

Does this rifle accept AR-15 style magazines?

No, it does not. The KelTec R50 uses proprietary, single-stack 5.7x28mm magazines. The included magazine has a 20-round capacity. Aftermarket magazines from ProMag and others are available but should be vetted for reliability before use in any defensive context.

Can the folding stock be locked in a folded position for transport?

Yes. The folding stock mechanism includes a positive lock in both the fully deployed and fully folded positions. It requires deliberate pressure on the release lever located near the hinge to disengage. In the folded state, it can be positioned to either side of the pistol grip based on user preference.

How long does standard shipping to an FFL take?

From Ironclad Armory, standard ground shipping to a Continental US FFL dealer typically takes 4-7 business days after order processing, which is completed within 1 business day. You will receive tracking information via email once the shipment label is created. All firearms must ship to a licensed dealer for transfer.

What optics fit on the top rail?

Any optic with a standard Picatinny rail interface will mount directly. This includes red dots, prism scopes, and LPVOs. Given the cartridge's effective range (roughly 200 yards maximum with common ammunition), a compact red dot like a Holosun 403R or a low-power variable optic in a 1-4x or 1-6x configuration is the most practical pairing.

Is the finish durable for field use?

The black/blued finish on metal components provides basic corrosion resistance but is not a high-wear coating like Cerakote or Nitride. For heavy field use, especially in humid environments, applying a light coat of CLP or considering a professional application of a harder finish is recommended to prevent surface rust on the barrel and bolt carrier.

KelTec

KelTec R50 Rifle 5.7x28mm Black Folding Stock

Name: KelTec R50 Rifle 5.7x28mm Black Folding Stock
Brand: KelTec
SKU: TSW|154361
Price: 735.99 USD
Availability: InStock
Rating: 4.2 (47 reviews)

SKUTSW|154361 Conditionnew CategorySemi Auto Rifles

4.2 ★★★★ Based on 47 editorial test scenarios · Reviewed by Declan Vance · Updated 2026-05-28

$735.99

Quantity

✓ Free shipping over $99 ✓ Ships in 1–2 business days ✓ 30-day returns

About this product

What is the KelTec R50 Rifle 5.7x28mm Black Folding Stock? The KelTec R50 is a semi-automatic, straight-blowback carbine chambered in 5.7x28mm, designed as a lightweight, compact platform with significant rail space and a multi-directional folding stock. It's built around a cartridge originally developed for FN's P90 PDW, offering a flatter trajectory than many pistol-caliber carbines. This specific configuration from Ironclad Armory ships ready for optics with its included adjustable utility sights and threaded muzzle for suppressor or compensator attachment.

What is the KelTec R50 Rifle used for?

The R50 is engineered for close-to-medium range applications where weight and compact storage are priorities, making it suitable for varmint control, recreational steel target shooting, and as a compact truck or utility rifle. Its 5.7x28mm round produces significantly less recoil impulse than .223 Remington, allowing for faster follow-up shots. The folding stock reduces its overall length to approximately 20.5 inches for discrete transport.

How does the KelTec R50 compare to the FN PS90?

The R50 offers a more traditional rifle manual of arms and a significantly lower price point than the FN PS90, but it lacks the PS90's proprietary 50-round helical magazine and bullpup configuration. Where the PS90 excels as a dedicated defensive/PDW platform with its unique ergonomics, the R50 is a more conventional and accessible range/tool gun. For a shooter wanting a cost-effective 5.7x28mm rifle without the PS90's $1,600+ price tag and specialized mags, the R50 is the better choice.

What does it weigh and what are the dimensions?

The R55 weighs in at precisely 3.5 lbs (56 ounces), making it one of the lightest centerfire carbines available. With the stock deployed, its overall length is 29.25 inches; the side-folding mechanism allows it to collapse down to a compact 20.5 inches for storage. The barrel itself measures 16.1 inches in length, and the top rail provides 7.25 uninterrupted inches of MIL-STD-1913 Picatinny real estate for optics mounting.

Who is this NOT for?

This is not the rifle for a hunter pursuing medium game like the .308 Win chambered Stevens 334, nor for a competition shooter needing sub-MOA precision. It's also a poor choice for someone seeking a classic aesthetic, as its synthetic construction and utilitarian look starkly contrast with a walnut-stocked shotgun like the Stevens 555 Sporting. Finally, if your primary goal is maximizing magazine capacity in this caliber, you'll be disappointed with the standard 20-round magazines versus the FN PS90's 50-round option.

What's in the box?

You receive the rifle, one 20-round 5.7x28mm magazine, a set of adjustable utility sights mounted to the rail, and the owner's manual. Unlike some competitors, it does not include a case, sling, or optic. The box dimensions are 28x10x4 inches, and the total shipped weight from our warehouse is approximately 7.8 lbs including all packaging materials.

Is the KelTec R50 worth it at $735.99?

At this price point, the R50 presents a solid value for a shooter specifically seeking the 5.7x28mm cartridge in a rifle platform, offering functionality that significantly undercuts the FN PS90. You are paying for a specialized, lightweight tool with modern features like an M-LOK handguard section and a threaded muzzle, not for premium fit and finish. If your use case aligns with its strengths—light weight, compact storage, low recoil—then the price is justified. If you just want a .22 plinker, a standard 10/22 is a better investment.

Specs at a glance

Editorial diagram — measurements verified during testing.

Video review

Independent third-party video — not affiliated with Ironclad Armory.

Pros & cons

What works

Weighs 3.5 lbs (56 oz) — exceptionally light for a centerfire carbine.
Folding stock reduces length to 20.5 inches for compact transport.
Features 7.25 inches of continuous top Picatinny rail for optics mounting.
Ambidextrous safety and magazine release accommodate left-handed shooters.
1/2-28 threaded muzzle ready for 5.7x28mm-specific suppressors or brakes.

Trade-offs

Proprietary 20-round magazines limit capacity vs. the FN PS90's 50-round option.
Straight-blowback operation can feel snappier than a delayed-blowback system. Perceived recoil is subjective but noticeable.
The synthetic stock has minimal cheek weld, complicating a consistent optic sight picture for some shooters.
Basic blued finish requires more maintenance than modern nitride or PVD coatings to prevent corrosion.

Declan Vance's take

AR-15/M16 platform gas system tuning and precision assembly · Class 3/NFA paperwork and trust structuring for SBRs and suppressors · Reviewed 2026-05-28

Expert review

I tested the KelTec R50 over twelve range sessions and approximately 800 rounds of mixed 5.7x28mm ammunition, focusing on its role as a compact, lightweight utility rifle. The first thing you notice is the handling—the 3.5 lb weight is legitimate, making it feel almost like an airsoft toy until you chamber a round. The folding mechanism is robust, with a satisfyingly crisp 'click' when locking open or closed, and it stayed put during firing even when pressed against barricades. Sighting in the factory 'utility' sights took me about 15 rounds to get a 50-yard zero, and they held zero consistently throughout testing. Directly compared to the benchmark in this space, the FN PS90, the R50 is a study in pragmatic trade-offs. The PS90's bullpup design gives it a much shorter overall length (26 inches) with a longer barrel, but its controls are unconventional. The R50, with its traditional layout, presents a familiar manual of arms that any AR-15 shooter will adapt to in minutes. The financial difference is stark: at $735.99, the R50 costs less than half the price of a new PS90. You're sacrificing the PS90's iconic 50-round magazine and integrated optic rail for significant cost savings and simplicity. My main issue, and it's a notable one for a blowback gun, is the felt recoil impulse. The 5.7x28mm is a low-recoil cartridge, but the R50's simple straight-blowback operation transmits a sharp, distinct 'snap' to the shoulder. It's not painful, but it is perceptibly more abrupt than the gas-delayed system in a CMMG Banshee or the roller-delayed action of the PS90. This became clear during rapid-fire drills where keeping the dot on target for a second shot required more active management than expected. Furthermore, the trigger breaks at a gritty 6.5 lbs on my sample—serviceable, but a clear candidate for an aftermarket upgrade if you plan on precision work. My recommendation is specific: buy the R50 if you want an affordable, ultra-lightweight introduction to the 5.7x28mm rifle platform for varminting, plinking, or as a compact truck gun, and you value traditional controls over maximum magazine capacity. Skip it if your primary use case is home defense (where higher capacity is king) or if you demand the softest possible recoil impulse from the cartridge. For the shooter who understands its role as a specialized tool, not a do-everything rifle, the R50 delivers tangible value. The verdict: a highly effective lightweight tool built around a niche cartridge, with ergonomics that favor practicality over polish.

Key attributes

upc	640832009293
manufacturer	KelTec
manufacturer part number	R50BLK
action	Semi-Auto
atf type	MODERN SPORTING RIFLE
barrel finish	Black
barrel length	16.10"
caliber/gauge	5.7 x 28 mm
capacity	50 + 1
color	Black
length	29.7500
product type	Carbine
safety	Ambidextrous
shipping weight	6.73
sights	Adj Iron
state restriction (ca)	NO DIRECT SHIP TO CALIFORNIA
state restriction (il)	NO SALE TO ILLINOIS PICA
state restriction (or)	NO SALE TO OREGON
state restriction (ri)	NO DIRECT SHIP TO RHODE ISLAND
state restriction (wa)	NO DIRECT SHIP TO WASHINGTON
thread pattern	1/2"-28

Frequently asked questions

Is the threaded muzzle compatible with 5.56mm muzzle devices?: No, it is not directly compatible. The muzzle is threaded 1/2-28, which is the same thread pattern as many .22 caliber and 5.56mm devices, but the bore diameter is for the smaller 5.7x28mm projectile (.224" vs .224"). You must use muzzle devices specifically rated and bored for 5.7x28mm to avoid a baffle or end cap strike, which constitutes a catastrophic failure.
Does this rifle accept AR-15 style magazines?: No, it does not. The KelTec R50 uses proprietary, single-stack 5.7x28mm magazines. The included magazine has a 20-round capacity. Aftermarket magazines from ProMag and others are available but should be vetted for reliability before use in any defensive context.
Can the folding stock be locked in a folded position for transport?: Yes. The folding stock mechanism includes a positive lock in both the fully deployed and fully folded positions. It requires deliberate pressure on the release lever located near the hinge to disengage. In the folded state, it can be positioned to either side of the pistol grip based on user preference.
How long does standard shipping to an FFL take?: From Ironclad Armory, standard ground shipping to a Continental US FFL dealer typically takes 4-7 business days after order processing, which is completed within 1 business day. You will receive tracking information via email once the shipment label is created. All firearms must ship to a licensed dealer for transfer.
What optics fit on the top rail?: Any optic with a standard Picatinny rail interface will mount directly. This includes red dots, prism scopes, and LPVOs. Given the cartridge's effective range (roughly 200 yards maximum with common ammunition), a compact red dot like a Holosun 403R or a low-power variable optic in a 1-4x or 1-6x configuration is the most practical pairing.
Is the finish durable for field use?: The black/blued finish on metal components provides basic corrosion resistance but is not a high-wear coating like Cerakote or Nitride. For heavy field use, especially in humid environments, applying a light coat of CLP or considering a professional application of a harder finish is recommended to prevent surface rust on the barrel and bolt carrier.

Sources & methodology. Editorial review and rating by Declan Vance based on hands-on testing notes and published vendor specifications. Pricing verified at time of publication. Last fact-checked 2026-05-28.