Guide

    Ruger Mark IV 22/45 22LR (MPN 40190) Review: Threaded, Optics-Ready Rimfire Pistol Built for Training

    Ruger Mark IV 22/45 22LR (MPN 40190): Threaded, Optics-Ready Rimfire Performance

    Introduction

    The Ruger Mark IV 22/45 in this configuration (MPN 40190 / UPC 736676401901) is a purpose-built rimfire semi-auto that blends the Mark-series’ well-earned accuracy reputation with a 1911-style grip angle and control layout. The result is a pistol that feels “centerfire familiar,” but shoots with rimfire economy—making it an excellent choice for high-volume range work, fundamentals training, and adding a suppressor or red dot without turning the gun into a project.

    What sets this particular Ruger Mark IV 22/45 apart is the combination of a 4.4-inch barrel, a factory threaded muzzle, and out-of-the-box optics readiness via a top Picatinny rail—features that typically push buyers toward more “tactical” rimfire models. If your goal is a training pistol that stays accurate, runs reliably with quality .22 LR, and is easy to maintain, this version checks the right boxes.

    Key Features and Specifications

    Below are the practical, buyer-relevant specs and what they mean on the firing line.

    • Caliber: .22 LR
      Affordable ammunition and low recoil make the Ruger Mark IV 22/45 ideal for developing trigger control, sight tracking, and cadence.

    • Action: Semi-automatic, fixed-barrel Mark-series design
      The Mark platform’s fixed barrel and internal bolt system are key contributors to its accuracy potential and consistent sight-to-barrel alignment.

    • Barrel Length: 4.4 inches
      This length balances holster friendliness with enough sight radius and velocity to make steel plates and bullseyes feel easy rather than “fussy.”

    • Capacity: 10+1 rounds (ships with two 10-round magazines)
      Ten-round magazines keep the pistol widely compliant and make for consistent training strings.

    • Sights: Adjustable rear sight
      Adjustable irons matter on rimfire pistols because .22 LR loads vary. Being able to fine-tune elevation/windage for your preferred ammo (standard velocity vs. high velocity) is a real advantage.

    • Optics Ready / Mounting: Factory Picatinny top rail (for red dots)
      A top rail makes it straightforward to mount common pistol optics. If you want a “trainer” that mirrors a defensive red-dot pistol’s presentation and dot acquisition, this is the cleanest way to do it.

    • Threaded Muzzle: 1/2"-28 (with thread protector)
      1/2x28 is the most common rimfire suppressor thread standard. This allows easy suppressor use (where legal) and also supports certain rimfire muzzle devices.

    • Grip/Frame: Polymer frame with 1911-style grip angle (“22/45” pattern)
      The 22/45 geometry helps 1911 shooters (and many modern pistol shooters) feel instantly at home. It’s also a strong ergonomic fit for training new shooters because the grip shape encourages repeatable hand placement.

    • Finish/Color: Black, blued (per provided product context)
      A classic, subdued finish that suits a range gun that will see lots of handling and holster time.

    • Signature Mark IV Benefit: One-button takedown
      Mark IV pistols are known for dramatically simplified field stripping compared with earlier generations—important on rimfire guns that get dirty quickly.

    Safety note worth knowing: Ruger issued a Mark IV safety-related recall covering Mark IV pistols (including 22/45 variants) manufactured prior to June 1, 2017. If you ever buy used, verify the serial number status and retrofit markings through Ruger. (This is less likely to affect a new-in-box MPN 40190 today, but it’s critical used-market due diligence.)

    Practical Applications

    The Ruger Mark IV 22/45 is at its best when you treat it like a “skills multiplier”—a gun that lets you train more for less, while still staying honest.

    1) High-volume fundamentals training

    This pistol is excellent for:

    • Trigger press and follow-through
    • Calling shots and tracking sights/dot
    • Strong-hand / support-hand only drills
    • Cadence work on steel

    Because recoil is minimal, errors don’t get “masked” by blast and muzzle flip. If your grip or trigger timing is off, the target tells the truth.

    2) Suppressor host (where legal)

    With the factory threaded muzzle, the Ruger Mark IV 22/45 becomes a natural suppressor host. Suppressed rimfire shooting is not just fun—it’s genuinely useful for:

    • Reduced noise and improved communication on the line
    • Better focus on sights and trigger without flinch-inducing blast
    • More comfortable training for new shooters

    If you’re buying a suppressor, be sure you’re current on federal requirements and your state/local rules. ATF’s current NFA processing time data can help set expectations if you’re planning a Form 4 purchase.

    3) Red dot training and “skills transfer”

    A red dot on a rimfire pistol is one of the fastest ways to improve:

    • Draw-to-first-shot efficiency
    • Visual patience (confirming acceptable wobble)
    • Transitions between targets

    The factory rail on this model makes the dot route straightforward, and the low recoil of .22 LR keeps dot movement easy to read.

    4) General range fun that stays accurate

    Some rimfire pistols are “fun” but inconsistent; the Mark platform’s fixed-barrel design and solid sighting system tend to keep groups tight enough that you’ll spend time improving—not diagnosing.

    Expert Analysis

    From a product-research perspective, this MPN 40190 configuration is compelling because it hits the modern rimfire “must haves” without forcing you into an overly large, front-heavy, or accessory-dependent build.

    What this model does especially well

    • Maintains the core Mark accuracy formula while adding modern mounting and threading.
    • Balances like a real training pistol rather than a novelty plinker.
    • Keeps ownership simple: Mark IV takedown is a major advantage on rimfire guns.

    Ammo and reliability expectations

    .22 LR is inherently variable across brands and even lots. While many shooters report excellent function with quality loads, expect to do the normal rimfire best practices:

    • Start with known reliable ammo (e.g., quality plated high-velocity loads) during early use.
    • Keep the chamber and bolt face clean—rimfire residue builds quickly.
    • If you see intermittent feeding issues, magazines are often the first place to inspect and clean.

    Accessory compatibility (high-value upgrades)

    Without turning your pistol into a money pit, the accessories that usually provide the biggest real-world return are:

    • A quality micro red dot (if training for dot shooting)
    • Extra magazines for efficient practice
    • A suppressor (where legal), which changes the entire shooting experience
    • A purpose-fit holster if you plan to run drills or field carry

    Legal and compliance considerations

    • Threaded barrels are restricted in some states/localities. Confirm legality before purchase or transfer.
    • Suppressors require NFA compliance and approval before you take possession.

    Conclusion

    If you want a rimfire pistol that feels familiar in the hand, is built for real training volume, and is ready for both optics and suppression, the Ruger Mark IV 22/45 (MPN 40190) is a strong, practical choice. The 4.4-inch barrel keeps it handy, the adjustable sights support precise zeroing, and the factory threading plus top rail provide modern flexibility without forcing you into a complicated setup.

    For most shooters, this is the sweet spot: a durable, accurate .22 LR pistol that makes you want to practice more—because it’s easy to run, easy to maintain, and rewarding on target.

    Sources