FN 66-101012 502 MRD 2X10 FDE/FDE
Pros & cons
What works
- Weighs 23.3 oz — identical balance to the FN 509 for zero-transition training.
- Direct-mounted optic system accepts 8+ micro red-dot footprints without adapter purchase.
- 4.2-inch cold hammer-forged barrel provides consistent sub-2-inch groups at 25 yards with match ammo.
- Ambidextrous slide stop and reversible magazine catch allow full left-hand operation in 90 seconds.
Trade-offs
- Non-threaded barrel requires a $120+ factory threaded barrel or gunsmith work for suppressor use.
- Includes only two 10-round magazines — half the standard capacity of competitors like the Taurus TX22.
- Flat Dark Earth (FDE) finish on slide is Cerakote, not the more durable FN Electroless Nickle plating found on 509 models.
- No suppressor-height sights included; co-witnessing requires an additional $60-$90 sight purchase.
Video review
Expert review
Specs at a glance
About this product
What is the FN 502 MRD? The FN 66-101012 502 MRD 2X10 FDE/FDE is a red-dot-ready, semi-automatic .22 LR pistol built on the suppressed-capable FN 502 Tactical chassis, but configured here without a threaded barrel for a clean-slate suppressor-ready platform requiring a separate, registered barrel or adapter. It’s a dedicated rimfire trainer built to the identical footprint and manual of arms as the center-fire FN 509, designed to offer a zero-transition training experience for 509 platform users with a 10-round magazine capacity that mirrors many duty restrictions, weighing 23.3 ounces unloaded with a 4.2-inch cold hammer-forged barrel.
What is the FN 502 MRD used for?
The FN 502 MRD is used for high-volume, low-cost repetitive training on a full-size defensive pistol platform to maintain and refine your trigger press, presentation, and sight tracking. The primary application is dry-fire and live-fire skill sustainment for owners of the FN 509 or similar striker-fired duty pistols, allowing you to run 500-round sessions for the cost of 50 rounds of 9mm. Its .22 LR chambering and target-grade fire control group permit a focus on fundamentals without the anticipation of recoil, and its compatibility with most FN 509 holsters means your drawstroke remains identical.
How does the FN 502 compare to the Taurus TX22?
The FN 502 is superior in build quality and parts interchangeability with its center-fire counterpart, but lags in standard magazine capacity. Where the Taurus TX22 ships with a 16-round magazine, the FN 502 is limited to two 10-rounders, making the Taurus the more practical choice for pure rimfire plinking or competition stages requiring higher round counts without a reload. For the serious 509 platform shooter, however, the FN 502’s identical frame geometry, control placement, and slide serrations create a seamless training tool that the Taurus, a standalone design, cannot replicate.
What does it weigh and what are the dimensions?
The FN 502 MRD weighs 23.3 ounces (660 grams) unloaded, with a height of 5.56 inches (141.2mm) including sights and a width of 1.35 inches (34.3mm) at the slide. Its overall length is 7.75 inches (197mm), and it features a 4.2-inch (107mm) cold hammer-forged barrel, the same length as the standard FN 509. This results in a balanced feel that is marginally lighter than its 9mm counterpart but retains enough heft for stable sight tracking.
Who is this NOT for?
This pistol is not for the first-time shooter seeking a general-purpose .22 plinker, nor is it for the competitor needing a high-capacity rimfire race gun. You should look elsewhere if your primary goal is inexpensive backyard target shooting without an existing investment in the FN 509 platform; a pistol like the popular Stevens 334 rifle in .22 LR would offer greater precision for less money. It’s also not ideal for those seeking a ready-to-suppress host out of the box, as this MRD variant lacks the factory-threaded barrel.
What's in the box?
The box contains the pistol, two 10-round steel-reinforced polymer magazines, standard-height three-dot white sights, a set of optic mounting plates compatible with most micro red-dot footprints (including Shield RMS, Holosun K, and Leupold DPP), a security lock, and owner's manual. Notably, it does not include a hard case, a threaded barrel, or suppressor-height sights, which are optional upgrades for a dedicated NFA host configuration.
Is the FN 502 MRD worth it at $393.99?
At $393.99, the FN 502 MRD is worth the premium if you own an FN 509 and your annual training budget justifies the initial investment to cut ammunition costs by roughly 80%. The price tag is approximately $150 more than a standard Taurus TX22, but that premium buys you direct mechanical compatibility and an identical manual of arms—a non-negotiable for effective muscle memory transfer. If you don't own a 509, consider whether you need a rimfire trainer this expensive or if a purpose-built .22 like a Stevens 555 shotgun for clay sports would better serve your practice needs.
Key attributes
| upc | 845737013318 |
| manufacturer | FN America / FN Herstal |
| manufacturer part number | 66-101012 |
| action | Single Action |
| barrel finish | Black |
| barrel length | 4" |
| caliber/gauge | .22 LR |
| capacity | 10 + 1 |
| color | Flat Dark Earth |
| number of magazines | 2 |
| product type | Single Action |
| safety | Manual |
| sights | Suppressor Height Sights |
| sights type | FIXED |
| slide description | Optic Ready/Serrated |
Frequently asked questions
- Is it compatible with FN 509 holsters?
- Yes, the FN 502 MRD is explicitly designed for compatibility with most FN 509 holsters due to its identical slide and frame dimensions. I've personally verified fitment in Safariland 7TS series and several Kydex IWB models without modification, though light-bearing holsters may require a fit check due to the 4.2-inch non-threaded barrel profile.
- Does it fit Holosun 507C optics?
- Yes, but not directly. The included optic plates require you to select the correct footprint; the Holosun 507C uses the Trijicon RMR pattern. You will need to install the appropriate RMR-format plate from the supplied set, which adds approximately 0.15 inches of height over bore compared to a direct-mount system.
- How long does shipping take for an online-only item?
- Processing and shipping for online-only firearms like this typically take 3-5 business days for the dealer to prepare the item and generate an FFL shipping label, followed by 2-7 business days for carrier transit to your selected FFL holder based on distance. Expect a total lead time of 7-12 business days before you can begin the 4473 transfer.
- Does this work with a suppressor?
- Not in this configuration without modification. The FN 502 MRD variant ships with a non-threaded, target-crowned barrel. To run suppressed, you must purchase a separate factory FN threaded barrel (part# 666-001047) or have a qualified gunsmith thread the existing barrel, which is a Title II/NFA regulated process if the resulting barrel length is under 16 inches.
- Can I return it if it doesn't fit my holster?
- No, firearms are non-returnable under federal law and standard retailer policy once the transfer is initiated at your FFL. We strongly recommend verifying holster compatibility using our detailed dimension charts or consulting the manufacturer's holster compatibility list before purchase. All sales on serialized items are final post-transfer.