If more than 8 million Ruger 10/22s sold make it America’s favorite rimfire rifle then the estimated 3 million Ruger MK I-IV series .22LR pistols sold must make it America's favorite rimfire pistol. Coincidentally both these best sellers were loosely modeled after the much coveted M1 Carbine and German Lugers of World Wars I and II. 

The MK series pistol has been a lot of things: a plinker, hunter, target gun, suppressor host, tactical weapon, competition shooter and even defense pistol. Suppressed Ruger MKII/III pistols have been widely used by U.S. and Israeli special forces for what they term as secret squirrel work. For the accuracy-focused customer, there is no more proven semi-automatic .22LR pistol than the forever-evolving Ruger Mark series. For the upgrader or competitor there are incredible aftermarket options that can elevate accuracy and ergonomics to a level never imagined by Bill Ruger.

Ruger MK Variants

The Ruger MK Series pistols have been wildly popular and continual sellers throughout their MK I, II, III, and now IV versions. Ruger also offers the 22/45 grip models which have significant cross-parts compatibility of uppers, triggers and magazines with just a baseplate change. The Ruger MK series pistol has featured plain and threaded barrels with skinny to heavy bull profiles ranging from 4 to 10-inches and the LITE ultralight sleeved tensioned barrels. Of course the aftermarket throughout the years has offered all sorts of unique barrel and configuration options as well. Sights on models have ranged from fairly crude to fully adjustable and fiber optic models, to top picatinny rails for red-dot mounting. The Ruger MK series has proven itself adaptable in nearly every environment and part of that flexibility has been the easy upgrade and customization options.

The MK series has improved through each evolution, but the MKIV series was a huge jump that included full CNC billet aluminum or stainless frames, spring-loaded magazine ejector, ambi-controls, and the major game changing upgrade of the push-button take-down design. Simply put, the previous MK I-III disassembly/assembly process was excruciatingly painful, so the elegance of a one-second takedown button deserves loud applause. Sadly, Ruger retained the infuriating magazine disconnect, but thankfully removed the MKIII jam-inducing chamber indicator. Overall the MKIV is a giant leap for the pistol, improving maintenance, upgrades, barrel swaps and reliability. 

Currently Ruger offers eight different MKIV product families that include the Standard, Target, Hunter, Competition, Tactical, 22/45, 22/45 Lite, and 22/45 Tactical families. The great thing is that nearly all the parts are interchangeable within the MKIV family even between 22/45 and MKIV series. As long as users swap magazine base plates the standard and 22/45 grip frames can be swapped between barrel assemblies, opening up an interesting aftermarket upgrade path. Most aftermarket manufacturers now offer versions of previous MKII and MKIII aftermarket upgrades in the MKIV versions. Two of the most prolific MK series aftermarket manufacturers are Volquartsen and Tandem Kross. Both offer dealer stocking programs with unique high-quality parts that elevate the accuracy, speed and ergonomics of the pistol from impressive to amazing.

Volquartsen

Volquartsen has been at the center of development for the Ruger 10/22 rifle and MK II/III and IV pistols since 1974, creating the most custom and accurate competitively renowned rimfires on the market. Volquartsen has evolved from a custom gunsmith shop to offering upgrade parts, complete upgraded firearms and even complete custom firearms with nearly every part of their own design made in house. If you want to upgrade an existing Ruger, all hee meticulously made parts Volquartsen features in its own firearms are available for the DIY upgrader. Their fully custom MK III/IV pistols complete with custom match barrel and billet lower receiver are offered in a wide range of configurations and color options. Volquartsen also offers custom upgrades and parts for various other Remington, Ruger and S&W models.

Tandem Kross

TK started as a home-office business in 2012 and grew as their unique parts began to draw more attention. Tandem Kross has been noted as one of the fastest growing rimfire manufacturers in the market and now offers custom upgrades for various Ruger, S&W, Browning, Taurus, Tippmann, Keltec, CZ, Walther and FN guns, plus 1911-22, 1911 and AR15-compatible firearms. For the Ruger MKII/III and MKIV owners, about the only parts Tandem Kross does not offer are the barrel assembly, bolt carrier and disconnectors. 

Complete Firearms and Upgrades

Complete custom match-grade pistols from Volquartsen give customers a factory-tested custom pistol option that already includes the highest tier of competitive accuracy and enhancements. Volquartsen offers a stocking dealer program of complete firearms, upgraded frames, competition pistol-barreled uppers, complete diamond-coated competition bolts, trigger upgrade kits, and individual parts plus a special order program for customers to order exactly what they want. 

Of note, Volquartsen offers a mindblowing 56 fully custom match-grade pistols across its Ruger MK Black Mamba, Classic, Mamba-TF and Scorpion series. They also offer over 30 complete competition pistol MKII/III and MKIV upper match-barrel assemblies and seven complete upgraded billet frames with MKII/II compatibility.

TK also offers 100% in-house fully custom Kraken lower MKIV frames loaded with all their custom match parts and stock Ruger 22/45 polymer upgraded “Tandemized” Frames. Tandem Kross does offer Tandemized Ruger LITE 22/45-barreled complete pistols in a number of color options. According to TK, the Ruger LITE is one of Ruger’s most popular models and they want customers and dealers to be able to purchase an out-of-the box with all the benefits of the TK upgrades. 

DIY Parts & Kits

Both Volquartsen and Tandem Kross offer simple DIY kits that range from trigger upgrades to bolt tuneup kits with more aggressive extractors and higher-reliability firing pins. Both companies also offer trigger upgrade kit options which also remove the magazine disconnect, plus grip options that range from stylish to competitively optimized. Other simple upgrades and accessories include TK’s ChamberMaid Swag to clean up and correct dry fire burrs, a speed loader, and the bolt-on Charging Ring.

Why Customers Upgrade

The Ruger MK series has a long reputation as an accurate pistol but the trigger has always been a weak point. Though the .22LR field-chambered barrel accuracy is capable, it is not at the same tier as Lothar Walther barrels on Volquartsen pistols with proprietary match-tuned chambers. The controls on the MK series pistols have always been designed for field hunting and not well optimized for the needs of the competitive shooter. 

If there is a need for accuracy improvements, the complete match trigger Accurizing kits from Volquartsen or Ultimate Trigger kits from Tandem Kross offer drastic improvements that include adjustable trigger take-up and overtravel. These crisp-breaking trigger kits are an instant upgrade for customers and are available for less than $200 from both manufacturers.

The next major step up is to replace the barreled upper with a match-chambered barrel and potentially upgraded firing pin and extractor. During my testing, the MKIV Volquartsen-barreled 3-inch Mini-Mamba with Competition Bolt plus an upgraded factory MKIV grip frame with the Volquartsen Accurizing Kit delivered groups half the size of factory barrels. Thanks to the MKIV’s push button take-down feature, the barreled upper was a near instant upgrade. The Volquartsen kit is simple enough for most customers to install themselves, but it also offers a dealer gunsmithing opportunities. With a suppressor installed, this build is also extremely quiet.

Featured Builds

The featured builds showcase MKIII and MKIV models. An MKIII Ruger LITE upper was  upgraded with a Volquartsen Competition Bolt and Complete competition billet frame complete with all their upgraded competition parts. The second build is based on a Ruger MKIV threaded stainless upper with a Tandem Kross complete Kraken lower frame with all their parts plus a TK compensator. In both cases, these builds improved accuracy by over 30% just with the trigger upgrades. The ergonomic upgrades also greatly improved manipulation and reloading speeds.

For the competitive-minded shooter who wants to shoot fast and reload even faster, the upgraded controls do increase overall manipulation speed. Volquartsen was the first to offer a unique spring-loaded magazine ejector and now Ruger and Tandem Kross offer that feature on their frames as well. This feature fires sluggish magazines from the frame and allows faster reloads. Optional oversized magazine base pads also improve magazine handling and improve speed. Both Volquartsen and Tandem Kross offer competition-style oversized controls including bolt release, safety and magazine release controls, plus forward thumb shelves for MKIV models. 

Regardless of how a customer upgrades, there has never been a better time to own a Ruger MKIV.