Ruger Mark IV 22/45 .22 LR 5.5″ Bull Barrel Pistol

Description

I remember the first time I field-stripped an old Ruger Mark II. Let’s just say it involved a mallet, a prayer, and a vocabulary that would make a sailor blush. That’s the single biggest reason the RUGER MARK IV 22/45 .22 LR 5.5″ BULL BARREL 10-ROUNDS exists. Ruger finally listened to decades of collective frustration and engineered a takedown system that’s genuinely simple. This isn’t just an evolution; it’s a revolution for one of the most iconic .22 pistols ever made.

The RUGER MARK IV 22/45 .22 LR 5.5″ BULL BARREL 10-ROUNDS is a modernized, easy-to-maintain .22 LR semi-automatic pistol. It features a one-button takedown, a 5.5-inch bull barrel for enhanced accuracy, a 1911-style grip angle (the “22/45” designation), and a 10-round magazine. Priced at $356.39, it’s built for endless plinking, training, and introductory shooting with minimal fuss and maximum reliability.

Let’s talk about that barrel first. The 5.5-inch bull barrel is the sweet spot for this platform. It provides the heft and sight radius to make you a better shooter without becoming muzzle-heavy or unwieldy. I’ve put thousands of rounds through various Mark IV configurations, and this barrel length just balances perfectly in the hand. It soaks up recoil—what little there is in a .22—and makes follow-up shots instinctive. The weight, coming in at around 41 ounces, is all in the right place, making it feel solid and stable, not clumsy.

Now, the headline act: the takedown. You press a button in the back of the receiver, pivot the mainspring housing down, and lift the upper receiver off the grip frame. That’s it. No gunsmithing required, no hammers, no aligning the hammer strut just right. Cleaning from the breech end is now a 30-second start-to-finish operation. This one feature transforms the ownership experience from a chore into a pleasure, encouraging you to actually maintain the pistol properly after a long day at the range.

The “22/45” part means it uses a grip frame that mimics the angle and controls of a 1911 pistol. If you train with a 1911 or similar platform, the muscle memory translates directly. The magazine release is at your thumb, and the grip feels familiar. It’s a brilliant design choice that makes this an outstanding, low-cost trainer. Pair it with a standard .45 ACP 1911 for a training session, and you’ll see the value immediately. The trigger is a classic Ruger Mark series trigger—clean, predictable, and easily improved with a plethora of aftermarket parts from companies like Volquartsen or TandemKross if you ever feel the need.

Specification	Detail
Model	Mark IV 22/45
Caliber	.22 LR
Barrel Length	5.5″ Bull Barrel
Capacity	10 Rounds
Finish	Black
Overall Length	Approx. 9.75″

Pros: The legendary Ruger reliability. The transformative one-button takedown. The perfect 1911-style trainer. Outstanding accuracy out of the box. A massive, friendly aftermarket for customization. Incredibly soft-shooting and cheap to feed.

Cons: The stock sights are functional but basic (many upgrade to a Picatinny rail and red dot). At 41 oz, it’s not a lightweight backpacking gun. Some purists might miss the “challenge” of the old takedown—I am not one of them.

So who is this for? Look, it’s for almost everyone. It’s the ideal first pistol for a new shooter due to its minimal recoil and safe, simple operation. It’s a must-have for any 1911 enthusiast looking for affordable trigger time. It’s a staple for seasoned shooters who want a dependable, accurate plinker for squirrels or steel plates. And it’s a fantastic host for a suppressor, with its threaded barrel variant being a popular choice.

Frequently Asked Questions

Q: Is the barrel threaded for a suppressor?

A: This specific model (40187) features a standard crowned bull barrel, not a threaded one. If you want a factory-threaded model, you’d want to look for the Ruger Mark IV 22/45 Lite or Tactical models. The good news is the aftermarket for threaded uppers is vast.

Q: What’s the difference between the “Mark IV” and the older Mark II/III?

A: The takedown system is the primary difference. The Mark IV uses a single button for disassembly, while the older models required a more complex procedure that involved partially pulling the trigger. The Mark IV is universally considered a massive improvement in user-friendliness.

Q: Are extra magazines easy to find?

A: Absolutely. Ruger Mark IV magazines are widely available and are often compatible across the 22/45 and standard grip models (just double-check the baseplate style). Brands like Ruger and Magpul produce reliable 10-round magazines for it.

This is the .22 pistol that fixes the one major flaw its ancestors had. It’s the benchmark for fun, affordable, and accurate rimfire handgunning. You can find the RUGER MARK IV 22/45 .22 LR 5.5″ BULL BARREL 10-ROUNDS available at firearms-missouri.com for Missouri residents and nationwide. See our site for current availability and remember, an FFL transfer is required for firearm purchases.