By Oleg Volk
Keltec began development of Carbine Magnum Rimfire 30 at least as far back as 2009. Known as RMR30 during its prototype stage, this 22WMR lightweight semi-auto went into mass production as CMR30 to avoid brand confusion with a Trijicon red dot optic. The carbine was designed as the companion to PMR30 pistol. The two weapons share magazines and have very similar fire control groups. Unlike PMR30, which uses blowback action to cycle low-power ammunition and locked breech for the rest, CMR30 is pure blowback. Since the threaded 16” barrel matches the intended burn rate of the ammunition better than pistol length barrels do, this simplified operation is entirely adequate for liability and negligible felt recoil. Combined with the bore nearly in line with the stock, this low recoil also means negligible muzzle rise and the ability to observe hits through the scope. In a select-fire version made for testing magazines, some rise and drift to the right is detectable, possibly due to the momentum of the empty casings streaming out at about 30 per second. Since the barrel is threaded for standard AR15 muzzle devices, and angled compensator could be of interest to those who want even greater
control in rapid fire.
The carbine is made up mostly of extruded aluminum, with a few laser-cut or machined parts and a molded plastic pistol grip completing it. CMR30 uses a hammer-fired action with a crisp trigger. That, coupled with the well-made barrel, makes it very accurate: 1.5MOA with a variety of loads is pretty respectable for a sub 4-pound autoloader. The full-length monolithic rail has room for a long varmint scope or a shorter optic in tandem with a thermal of night vision device. The Picatinny rail under the forend has room for a bipod, a light/laser and a foregrip. The extending stock is free from wobble, and even though a strong sideways impact would probably damage it, the gun would remain functional. With the stock collapsed, it’s only 22.7” long, short enough to hang under a jacket ready for action. Safety lever, charging handles, and the heel magazine release are ambidextrous. Bolt stop lever is on the left side only.
Maintenance is simple: pull one pin in the back of the receiver and the pistol grip comes off. The bolt, guide rod, and spring come out for cleaning. No further dis-assembly is needed. The gun runs very cleanly: even with a sound suppressor, I only had to pull it apart after over a thousand rounds. The weapon was full of carbon and unburned powder flakes but still ran perfectly.
Having had a pre-production sample of CMR30 since 2010, I’ve been an enthusiastic adopter from the start. The carbine made the most of the marginal cartridge while giving superb ergonomics. In common with FN P90 and HK MP7, CMR30 shoots a lightweight .22 projectile. Unlike 5.7×28 and 4.6×30 cartridges, 22WMR isn’t optimized for penetration of soft armor but excels with controlled expansion bullets. In the 40gr weight recommended for CMR30, most loads are either expanding soft points suitable for small game hunting or FMJ for target practice. FMJ at 1950fps does burn right through 1/4” aluminum diamond plate that showed only a slight divot from 9x19Luger and an even less obvious trace of 22LR bullets. What it lacks in power, this carbine makes up in capacity: 30 shots instead of the usual 10. CMR30 weighs only 3.8 pounds in base configuration with Magpul backup sights, so even the smallest adult or teen defenders can use it to good effect. Combined with the variable length collapsible stock, these features make it a viable personal defense weapon even for people who couldn’t heft a more conventional rifle. We have trained several people with minimal upper body strength and CMR30 really shined in giving them respectable firepower in a light package with simple manual of arms.
While the public release of CMR30 was delayed by concerns about possible federal bans, the design got improved in subtle but important ways. For example, the non-reciprocating charging handles were extended with bolt-on pieces to give them a forward rake so that fingers can’t slip off. The two-piece construction allows the user to shorten one side or the other if desired to reduce snagging. The undersized wire loops intended for sling attachment have been enlarged to accept a wider variety of connectors. But the overall design was sound from the start. It’s quite accurate, and even works well with sound suppressors attached. Used with a Gemtech 22WMR model, it reduced the already moderate blast to almost nothing. Due to supersonic bullets, this caliber is still not fully ear safe even suppressed.
The imperfections of the design are common to CMR30 and PMR30, all stemming from the cartridges and the magazine they use. This double-stack, double-feed polymer magazine is feather-light and inexpensive, but loading it takes some effort. The first 25 rounds are fairly easy, the remainder take some skill to insert without damaging the thin walls of the rimfire cases with the rims of those above them. At this time, no mechanical loader is available. For casual use, I simply load 25 rounds, with the standard 50-round ammunition box filling two. For full capacity, I am eagerly awaiting a solution promised for mid-2016 from Tandemkross which would solve this issue. It would also protect the heel release from accidental activation, something that has occasionally happened when shooting prone and wearing bulky gloves.
While 40-grain ammunition is recommended, the carbine also works with 30-grain and 50-grain loads. The lighter bullets consistently reach 2250fps ranges, with CCI TNT and V-Max exceeding 2300fps. At the time CMR30 came out, that meant 5.7x28mm performance at half the price. Even as the cost of 22WMR ammunition has recently increased, it remains far more available than the more exotic PDW cartridges while offering similar performance. Compared to FN PS90, CMR30 is also 40% lighter. Conventional wisdom is that rimfire cartridges are not reliable enough for defensive use, but I have never actually experience a mis-fire with 22WMR in over 6,000 shots fired over the past five years. The real issues a with 22WMR are the relative fragility in handling and the considerable surface area relative to the recoil thrust available for extraction, the same problem 410 shotshells have. CMR30 has shown consistent reliability of extraction, making it a non-issue. The same narrow case diameter is an advantage for magazine capacity, with 30 rounds fitting in a magazine the size of a 5.7 20-rounder. A centerfire version has been discussed but Keltec is constantly oversold on the rimfire original, so the introduction of new calibers may have to wait.
Most of the accuracy testing I’ve done has been with 3x prismatic scope from Vortex. Since every type of CCI ammunition tried yielded the same 1.5MOA, I strongly suspect the optic or the shooter is the limitation, not the mechanical capability of the carbine. The long optic rail allows high-magnification scope installation, and that’s what I would recommend for varmint control. That, combined with a bottom rail extension to cantilever the bipod closer to the muzzle, would give a steadier shooting platform and improve accuracy to make rodent removal practical out to about 175 yards at which 22WMR goes transonic. Another suggested improvement would be gluing moleskin to the outside of the buttstock struts for a more comfortable cheekweld in cold weather. None of the changes are expensive. The important components – the action, the barrel and the trigger – are all excellent and ready to perform straight out of the box.
CMR30 was eventually released in 2015 and has been extremely popular since. Lighter, less expensive and simpler to operate than its direct competitors, it’s been flying off the shelves at stores. The light weight and compact dimensions come are especially important when traveling by air or by motorcycle. For shooters used to PMR30, the similarity of the manual of arms is yet another bonus. Beyond its obvious utility as a varmint eradicator and a light defensive weapon, CMR30 is just an extremely fun gun to shoot.
|This article first appeared in Small Arms Review V20N8 (October 2016)|