The Ruger Mark series of 22 Long Rifle (LR) pistols is ubiquitous in the history of firearms. And with nearly 75 years of legacy, it’s understandable.
The original Sturm, Ruger & Co. semi-automatic rimfire was introduced in 1949 as the Standard. Its name was later changed to Mark I, and since then, three subsequent generations of Mark-series pistols have been made, including the latest Mark IV.
The Mark IV is arguably the best thus far. With improved ergonomics, like a simple push-button takedown, the Mark IV is among the top rimfire pistols a shooter can buy today. And with all that history, and with millions of models produced, the aftermarket support is daunting. It is simple to transform a simple Mark IV into a Space Force-looking blaster. And that’s precisely what I plan to do.
TANDEMKROSS
TANDEMKROSS is a well-known name in the rimfire community. As a company, they produce a wide range of products for various rimfire platforms. The company was founded in 2012 when two software developers, who had experienced a bad day at the range filled with failures to feed, stuck magazines, and more, set out to develop simple, reliable solutions for common firearm problems.
What began as a single part sold from a home office quickly grew into a New Hampshire–based company. TANDEMKROSS is now known for producing American-made aftermarket accessories for rimfire firearms.
Over the years, Tandemkross has expanded its catalog to become one of the largest in the rimfire industry and has formed notable partnerships. The company also became an active supporter of competitive shooting, progressing from Bronze to Platinum sponsorship of the NSSF Rimfire Challenge.
In 2024, industry veteran Tom Sullivan joined co-founder Bryan Haaker as a co-owner, marking a new phase of growth. Today, Tandemkross remains dedicated to “making good guns great” through innovation, quality manufacturing, and a strong connection to the shooting community.
Okay, enough with the corporate talk, let’s get to guns.
SILENCER SHOP MARK IV
This variant, the Ruger Mark IV 22/45 Tactical Pistol (what a name), is a Silencer Shop Exclusive, a dedicated suppressor-ready .22LR pistol designed for reliability and quiet shooting. It features a 3-inch cold hammer-forged barrel that’s threaded 1/2″-28 for quick attachment of muzzle devices or suppressors, plus a top Picatinny rail for an optic.
As mentioned earlier, Ruger’s simple one-button takedown system makes maintenance easy. The 22/45 name comes from the pistol’s adoption of a 1911-style grip angle and the use of 1911 grip panels. Rounding everything out, this Silencer Shop Exclusive pistol has a 10+1 capacity, ambidextrous safety, and a slim 7-inch overall profile, making it an ideal rimfire trainer or suppressed range gun.
On its own, this pistol is a nice addition to anyone’s collection. However, after talking with my friends at TANDEMKROSS, this pistol can go to a whole new level.
#TANDEMIZED
TANDEMKROSS offers a wide range of parts and accessories to upgrade your Mark IV pistol. While you can mix and match parts, the simplest choice is to select the fully assembled Cthulhu Lower. This lower is a machined aluminum replacement for the factory polymer frame, providing increased strength, improved ergonomics, and a tighter fit between the upper and lower.
It arrives preassembled with TANDEMKROSS performance upgrades. This includes a larger, textured trigger guard for better control, a refined grip with a textured backstrap, an extended magazine release, upgraded grip screws, a comfortable hiveGrip, and an adjustable, competition-ready trigger.
Instead of the standard takedown button, this lower features a takedown screw that greatly reduces movement between components, leading to enhanced stability and more consistent shooting performance.
The Cthulhu improves ergonomics and offers options that Ruger itself only dreams of. It truly is transformative.
TANDEMKROSS offers the Cthulhu in several colors, including red, green, black, and flat dark earth. Since the Silencer Shop Mark IV I chose is gray, I selected a black Cthulhu lower to complement it. Additionally, only the upper on the Ruger Mark IV is serialized. That means the lower can be shipped to your house without an FFL transfer.
Of course, you don’t have to go to this extreme. Most of the parts on the Cthulhu are available separately, and you can customize your pistol as you like. That’s the benefit of customization. The finished product reflects your vision.
EVERYTHING ELSE
While the Cthulhu lower was the primary part of this build, I picked up a few other items. I’ve listed them below:
TANDEMKROSS Halo Charging Ring for Ruger Mark IV & 22/45: Operating the slide—err, action?—of any Ruger Mark-series pistol can be challenging. Additionally, I notice there isn’t enough material to get a solid grip, which makes it hard for new shooters or those with dexterity issues to operate it.
Constructed of lightweight, aircraft-grade aluminum, the Halo Charging Ring improves grip and leverage for easier charging without adding extra weight to the pistol or affecting its action. This is a must-have.
TANDEMKROSS Shadow Mount V3.0: I thought this would be a cool accessory to add to the pistol. It provides a direct mounting solution for popular red dot sights, eliminating the need for a rail and a rail mount. This keeps the optic closer to the bore. However, there’s an important line I DID NOT read: “this product does NOT fit model 40179 (SILENCER SHOP Exclusive).” Whoops.
Standard Mark IV pistols use a three-hole pattern, while the Silencer Shop-exclusive model uses a four-hole one. I’m not perfect; I make mistakes. Luckily, my father has a Mark IV, so I’m sure he can get use of this mount. While I might not be using it for this build, I still thought it was worth mentioning—learn from my mistakes.
Vortex Defender-ST: Of course, since this pistol lacks iron sights, a red dot was necessary. I already had a Defender-ST on hand, so I chose that. I’m a big fan of this optic and of Vortex.
This red dot offers a range of features and comes at a very affordable street price. It comes with a wide selection of hardware to attach it to various pistols, as well as a Picatinny mount, which I used for this project. More importantly, Vortex covers every product with its VIP Warranty. This ensures that, if anything happens, Vortex will stand behind the product.
SilencerCo Warlock II: Perhaps the most important accessory, the suppressor. Now, there are a ton of quality rimfire suppressors on the market. The Warlock II offered a straightforward and affordable option, but the company recently discontinued it. I’ve used this suppressor on all kinds of 22 LR rifles and pistols, and it has performed well. Its major drawback (and why it was affordable) was that it was only rated for 22 LR, limiting its viability compared to other options.
In its place, I’d recommend the SilencerCo Sparrow.
ZOOMING OUT
This really is an out-of-this-world pistol. The final product looks more futuristic than typical. But the upgrades raise the bar for what the Mark IV platform can do.
Unfortunately, in Northeast Ohio, the weather has worsened—winter is here. This change has disrupted my range schedule, so I haven’t been able to shoot it yet. That said, I own several TANDEMKROSS products for different platforms. They all perform wonderfully and truly improve the shooting experience. Make sure to check out TANDEMKROSS for your next rimfire adventure.
