The FN 502 MRD is a .22 LR semi-automatic pistol that runs single-action only with an ambidextrous manual safety. It holds 10+1 rounds, has a 4-inch barrel, and measures 7 inches overall. The optics-ready slide accepts a variety of red dot sights without modification. Weight is 22.50 oz (1.41 lbs). Frame is black textured polymer; slide finish is black PVD. 
 

Key Specifications 

• Brand: FN 
• Model Name: 502 MRD 
• Caliber: .22 LR 
• Action: Single Action Only (SAO) 
• Capacity: 10+1 rounds 
• Barrel Length: 4 inches 
• Overall Length (OAL): 7 inches 
• Grip Material: Black Textured Polymer 
• Safety Type: Manual Safety (Ambidextrous) 
• Finish Color: Black PVD on slide; matte black on frame 
• Weight: 22.50 oz (1.41 lbs) 
• Height: 5.40 inches 
• Width: 1.40 inches 
   

Detailed Features 

The optics-ready slide is the distinguishing feature here -- most .22 trainers at this price level don't offer it, and it lets shooters practice optic-based aiming without running their primary carry gun's round count up. The ambidextrous manual safety works for both-hand shooters. Ships with two magazines. Textured grip holds well without gloves. 
 

Target Audience 

New shooters learning trigger control and recoil management; experienced shooters using it as a low-cost optics trainer for a carry gun setup. 
 

Usage Scenarios 

• Range training sessions focused on trigger discipline and sight alignment 
• Optics practice with a red dot before running the same setup on a centerfire 
• Competition classes where .22 is allowed and ammo cost matters

Owners of the FN 502 MRD point to the optics-ready slide and the comfortable grip texture as the strongest selling points. For a .22 practice gun, having the option to run a red dot in the same footprint as a carry-configured pistol is genuinely useful.

Function with quality ammunition is generally reported as reliable. The lightweight construction makes long range sessions easy. Trigger opinions are mixed -- acceptable to most, but a subset find it lacking crispness compared to the competition. The 10+1 capacity is standard for the class. Accessories and aftermarket parts are harder to source than for established .22 pistol lines. Some owners note slightly more felt recoil than expected from .22 LR during rapid fire, likely due to the lighter frame.