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The M4 carbine platform, often seen as the "natural evolution" of the M16 rifle, has been a media icon and the standard upon which all other military small arms are judged for years now, with countless manufacturers trying to duplicate it even in the world of rimfire sporting arms. Chiappa Firearms − the Italian company, also operating an US-based branch in Dayton (Ohio), now famous for its product line including countless rimfire military-style replicas as well as the Rhino revolvers − might have just got it totally right: the MFour-22 is probably the best .22 Long Rifle replica of the M4 platform we've ever seen − so faithful, in fact, that many parts (including working parts, such as the entire trigger group) are interchangeable with the original and with most of standard AR-15 based rifles and carbines out there.
Up until the recent past, those shooters who seeked an AR-15 lookalike rimfire carbine had to settle for a vaguely resembling clone, or to purchase a caliber conversion kit for an original rifle; said conversions generally consisted in a brand new breechbolt group to replace the original with, including a new barrel section that had to be installed inside the original .223 chamber. These rimfire kits had no provision for a new barrel, as they used the original barrel of the rifle or carbine they were installed into, and as such they suffered from the fact that the original bore and rifling pitch are too wide and long for the small .22 caliber round.
This kind of conversion kit went to slowly but steadily disappear from the market as complete upper halves replaced them (and as a matter of fact, Chiappa also markets the Mfour-22 upper receiver as a stand-alone conversion kit for centerfire AR-15s!), and at the same time, gunmakers launched new and more accurate rimfire replicas.
That's the case for the MFour-22: this small, rimfire semi-automatic sporting carbine is so faithful to the original M4 platform (more specifically, the Chiappa Firearms company patterned this replica after an A3 variant with a flat-top receiver), that some slight modifications had to be implemented on purpose on the design to prevent the MFour-22 lower receiver from being employed on an original AR-15 upper by mistake.
Quite a lot of parts on the Chiappa MFour-22 carbine do match the typical specs of the AR-15/M16/M4 platform − we can't definitely call this a "Mil-Spec" rifle, but that's definitely one of the most faithful, if not THE most faithful overall, M4 rimfire knockoffs we ever had the pleasure to try out.
These include: the buffer tube threads on the lower receiver; the pistol grip interface; the STANAG 4179/USGI M16 magazine well; the entire trigger pack, including all pins and the entire safety lever; the MIL-STD-1913 Picatinny rail (although manufactured out of polymer rather than aluminium); the handguard and the way it attaches to the receiver and the front sight base; and quite a lot more.
Chiappa's quest for perfect accuracy went as far as to reproduce some details that would otherwise be useless on a rimfire: that's the case for the forward assist button, which is a merely cosmetic feature and won't intervene on the bolt at all, but is nonetheless spring-loaded and can be pushed to obtain a faithful feedback.
That's not a meaningless exercise of style: it has its reason to be. Faithfulness down to these small details allows the MFour-22 to be used for training purposes, both for sports shooters and professionals.
That's the reason why the MFour-22 also features a reproduction of the hold open release button − totally dummy and molded in the polymer lower receiver − and an appendix under the front sight base that duplicates the look of the original bayonet lug but can't be used for that purpose.
Another simulated, non-working detail is the birdcage-style flash hider. That has been done to make the MFour-22 compliant with several local and State laws that ban specific "assault weapons" in some jurisdictions in the United States according to a list of features. Nonetheless, both the flash hider and the front sight base can be removed and replaced with original AR-15 parts, although frankly there's no real need for a flash hider on a .22 rimfire...
The Chiappa Firearms' MFour-22 semi-automatic carbine comes issued with two magazines and a detachable carrying handle which integrates the rear sights. The gun itself is totally made out of fibreglass and carbon fiber -reinforced polymer. Only differences are the bolt and bolt group (die cast metal) and its guides (stamped metal), the springs, the entire trigger group, the front sight base, the fake flash hider and other smaller metal parts, all made out of stainless steel; the barrel is cold-hammer forged out of a 4140 steel bar.
The overall weight of the carbine ranges around 2.5 kilograms (roughly 5 pounds and a half) when empty and without a carrying handle, and reaches up to 3 kilograms (about 6.6 pounds) with a carrying handle and a full magazine; that makes it just a little bit lighter than the original M4-A3, whose weight tops up 2.84 kilograms (6.26 pounds) empty.
The currently-manufactured and distributed Chiappa Firearms MFour-22 carbines are built out of GEN-II polymer, a synthetic material conceived by Chiappa itself and whose resistence and strenght properties are much akin to those of aluminium. The 16-inches barrel is cold-hammer forged out of a bar of 4140 stainless steel, it's black-finished and features six right-handed grooves with an 1:16" pitch − the industry standard for .22 rimfires.
The stock is manufactured out of the same GEN-II polymer used to build the rest of the gun; despite the MagPul-lookalike design, it comes as fixed (non-telescopic) as a factory standard − once again, to comply with some U.S. State laws that ban guns from private ownership according to some feature lists.
However, since the dimensions are totally MIL-SPEC, and so is the threads on the rear of the lower receiver that keep the fake buffer tube itself, the entire stock assembly can be removed by the user and replaced with a real-life buffer tube (with no real buffer and spring inside, as they'd be totally useless on a .22 rimfire) so to mount a real-life collapsing stock. Same goes for the pistol grip: it's installed on the MFour-22 exactly like it'd be on any full-caliber M4-type carbine, and as such, it can be removed and replaced with other compatible aftermarket models.
The single stack detachable magazine is also made out of GEN-II polymer, and will hold five, ten or twenty-nine rounds of .22 Long Rifle ammunition, according to the local laws and regulations applying where the carbine is sold. It features a side cut with a small lever that will allow the shooter to manually push the elevator down to ease the loading procedures. One drawback of this magazine, however, is that it should never, ever be kept loaded when the gun is not in use, not even for short amounts of time, as the elevator spring would get ruined very quickly. Said warning is also found on the instruction manual for the MFour-22.
The detachable carrying handle − an exact replica of the M4 original part − is also made out of GEN-II polymer rather than aluminium alloy, and it integrates the standard L-shaped diopter sight of the AR-15, with a ballistic drop compensation drum that's set up to 600 metres in distance. The manual for the MFour-22 states that these distances are set because this is an exact replica of the original, featuring .223 Remington caliber settings, so these should not be kept in consideration when zeroing the sights.
The carrying handle is installed upon a top Picatinny rail through a pair of small screw knobs; it's quite sturdy, but that's still polymer after all, so once it is removed, the rear sight may beed to be re-zeroed upon installation.
We thus warmly suggest our readers to leave it where it is, or to remove it permanently and replace it with an optical gunsight − we used a Leupold Prismatic 1x14mm sight with integrated magnifier to test the MFour-22 at the range.
Field-stripping for the Chiappa Firearms MFour-22 carbine follows step by step the procedure for the disassembly of the original M4, starting from the removal of the magazine and the clearing of the chamber.
Once that's done, the user should remove the front pivot pin and the rear takedown pin, thus enabling the removal of the upper receiver from the lower receiver; at this point, the bolt group may be removed from the upper for standard cleaning and maintenance proceduresby racking the cocking handle back.
The technical layout of the MFour-22 carbine departs from the original M4 almost proportionally to the faithfulness of the external appearance: while the cylindric bolt of the MFour-22 carbine is indeed coaxial to the barrel and inserted in the upper receiver, all the rest is totally different.
The heart of the MFour-22 carbine from Chiappa Firearms lays in the bolt group and its guides, with an integrated main return spring, which as a matter of fact is reminiscent of the legendary Ciener-Atchisson .22 conversion system under many points of view, and particularly in the axially-inclined, thick precision-cut stamped steel guide. Featuring no gas system whatsoever, the Chiappa Firearms MFour-22 carbine is a simple blowback-operated closed-bolt semi-automatic gun.
The bolt itself is a die-cast two-parts piece, and features a curved extractor and a chamfering that allows the dust cover on the ejection window to operate just like it does in any AR-15 rifle or carbine; it also features a recoil spring with a top-mounted guide rod, linked to the rear die-cast metal buffer; all is kept together with pivot and spring pins. Ejection is achieved through a fixed ejector, milled out of the left steel guide.
It must be mentioned that there's an alternative to the purchase of the MFour-22 as a stand-alone gun: the upper receiver of all the MFour-22 versions is sold by Chiappa Firearms as a conversion kit for standard AR-15 -based rifles and carbines, and is fully compatible with all AR-15 lower receivers (while the MFour-22 lower receiver is NOT compatible with AR-15 uppers!). So you may convert your own AR-15 with a .223-type lower (thus meaning that it may either be chambered for 5.56mm/.223 or any other caliber AR-15 rifles and carbines come into these days, as long as it's inferior to 7.62mm) to .22 rimfire by simply stripping it and replacing the original upper receiver with a Chiappa Firearms MFour-22 upper.
While technically feasible, this conversion may be restricted, or outright forbidden, in some jurisdictions: check your local laws and regulations before proceeding to the conversion!
Because said restrictions apply in several Countries, Chiappa Firearms modified the MFour-22 carbines sold in many places worldwide so that their upper receivers may not, as a matter of fact, be used as conversion on standard AR-15 lowers. Once again, please check your local laws and regulations − and more importantly, check with the company or see the instructions manual for the specs of the MFour-22 carbine as sold in your local jurisdiction − before even trying!
We tested the Chiappa Firearms MFour-22 semi-automatic carbine with two different types of commercial .22 Long Rifle ammunition: the 40gr. GECO "Rifle" lead round nose bullets − an "easy" load after all − and the much more powerful 36gr. conic-flanged Remington Wasp ammunition − these being, the "Solid" variant of the much more common Remington Yellowjacket round.
After a little bit "running-in", the Chiappa Firearms MFour-22 resulted extremely accurate and super-fast firing, with a good and satisfying recoil sensation with no muzzle flash whatsoever and such a low noise signature that bystanders may as a matter of fact stand a few feet away from the shooters and normally conversate with no need whatsoever for earing protections.
The MFour-22 is extremely fast to handle and its ergonomic layout is a perfect replica of the M4's; as such, trained users will get accustomed to it very easily thanks to the muscle memory, and at the same time, it will turn handy as a safe and cheap way to train newbies to the use of the AR-15 weapon system.
The hold-open and magazine release procedure are, as a matter of fact, the only options: the gun features no real hold-open device − the bolt will remain open after the last round has been fired because the magazine elevator will block its travel − and as soon as the empty magazine is removed, the bolt will slam closed and will have to be re-cocked when a fresh magazine is slabbed in. Also, the magazine release is not of the free-fall type, and the removal should be performed by grabbing the magazine with the weak hand, pushing the magazine release putton with the thumb, and pulling the magazine out.
Chiappa Firearms Mfour -22
Technical Specs
| Manufacturer | Armi Chiappa S.n.c. Italy |
| Model | Mfour-22 rif. 500 – 076 TAN |
| Type | Rimfire semi-automatic carbine |
| Caliber | .22 Long Rifle |
| Working system | Semi-automatic, blowback-operated |
| Barrel lenght | 406 mm / 16" |
| Rifling | 6 grooves, RH, 1 pitch in 16" |
| Feeding | 5-, 10- or 28-rounds detachable single-stack polymer magazine |
| Trigger | Single action, internal hammer |
| Stock | Polymer, fixed |
| Sights | Front sight adjustable for elevation, rear sight with BDC drum mounted on detachable carrying handle, adjustable for windage |
| Safeties | Manual trigger safety |
| Overall weight, empty | 2.5 kg. / 5.51 pounds |
| Overall lenght | 870 mm / 34.2" |
| Materials | Carbon
steel for barrel, Front Sight Base and smaller metal parts; fibre-reinforced upper and lower receiver; die-cast metal alloy bolt |
| Finish | Matte black on metal parts; factory black polymer |
| Price | € 603.50 / $527.00 |
