Like absolutely everyone who shoots, I feel the impacts of either not being able to get ammo or the unwillingness to pay the rising prices for centerfire rounds. Many of us saw the crazy ammo prices of the last few years. We backed into our caves and barricaded the doors. We ceased critical range practice time until we could again afford to feed our firearms.
Others hit the limit of home-based solitude. They decided to stop sitting and staring at the amazing AR-15s (we spent so much time customizing). We hit the range for low round count micro training to retain some level of muscle memory.
Recently, I was again reminded of how awesome AR-15 .22 LR caliber adapter kits and dedicated AR uppers are. I spent a day at the range doing some fairly intense barricade training. An entire 500-round brick of .22 LR with two AR-15s were put to work.
One with a simple drop-in .22 LR conversion and the other with a dedicated .22 LR upper build. Each has its own purpose. There are a couple options to consider. They range from being able to shoot .22 LR through your unmodified .223/5.56-chambered AR and the options of dedicated .22 LR-barreled components and uppers. Hopefully, most of us have a few bricks of .22 LR that we can part with to get our ARs on the range and get us shooting, training, and having fun again.
CMMG Bravo & Dedicated Kits
CMMG offers the slip-in .22 LR to .223 adapter style or dedicated .22 LR barrel collar type kit. The adapter style includes the complete slide-in bolt, spring, guide, and adapter assembly with an adapter that looks like a .223 case on the end. One kit facilitates the .22 LR to a .223 AR barrel chamber conversion. The other, with similar components, supports a dedicated .22 LR-barreled upper. It sounds a little like garage-level engineering. However, over the years the refinement CMMG has done to improve reliability and fit is quite impressive.
CMMG Bravo .22 LR Conversion Kit
CMMG has done well with delivering a high-quality, drop-in, .22 LR AR conversion kit for around $240. The kit typically includes the complete bolt carrier group assembly and 1–3 magazines, depending on the kit. This kit was initially developed as a low-cost training option for the military M16 and should be viewed as a tool to work through your basic presentation drills, barricade work, and having fun just plinking.
Generally, I set the expectation that this is a good bang-the-steel trainer and far from something for target work. However, sometimes you get lucky and find a particular AR build or ammo that can deliver very impressive results. For whatever reason, Faxon and Ballistic Advantage barrels have delivered very good accuracy for me with these kits and match-grade ammo. Sadly, however, some of my other super-custom hyper-accurate rifles are not great at all with these kits.
Though CMMG offers upgraded parts and kits that deliver full last round hold open. The entry-level Bravo kits rely on an extended follower in the magazine to simulate the bolt lock back. In the Bravo kit, removing the magazine closes the bolt. Once a fresh mag is inserted, the charging handle needs to be cycled. The cost-per-shot savings do not take long to add up.
The CMMG kit has become an industry standard for using your AR-15 chambered in .223 to shoot the inexpensive .22 LR round and is available with either 10 or 25-round magazines. With this kit, if you have an AR-15, you also have a .22 LR trainer version as well. The kit works reliably, is crafted from high-quality stainless steel, and can be maintained easily. CMMG even provides individual replacement parts.
The caliber conversion adapter on the end of the slide is basically a secondary breech in the shape of a .223 case, with a complete bolt and spring assembly that clips into the caliber conversion adapter. All the user needs to do is slide out their bolt carrier group, slide in the conversion into their AR-15, slip in a .22 LR Black Dog/CMMG magazine, and they are ready to shoot .22 LR in just a few seconds.
Since .22 LR bullets are also typically .222–.223 in diameter, they can shoot down the lands of a .223 Remington or 5.56 NATO barrel just fine. The are a couple factors that impact accuracy. First, the .22 LR bullet makes about a 1.5-inch jump through the adapter and into the barrel rifling lands, which degrade accuracy. The .22 LR usually does best with a slower 1:16 twist vs AR .223 barrels with 1:7, 1:8, or 1:9 twist, which tend to overspin the bullets and erode accuracy.
Notably, after using and testing the CMMG kits in a variety of AR-15s over the years, there are some ARs that shoot shockingly great even with cheap ammo and others that really need match-grade ammo to obtain usable hunting-level accuracy. Accuracy expectations should be 2–6-inch groups at 25 yards from bulk pack ammo.
This is more than enough to support fundamentals training. Point of impact at 25 yards will be about 3 inches lower than expected from your typical 200 or 300-yard AR zero. However, I usually adjust this with a few turret clicks to ensure I am mentally training my offsets correctly.
As with any of these kits, it is recommended that a light barrel cleaning be completed every few hundred rounds. Then, you should shoot a few .223 rounds, before a full cleaning to blow through any residual .22 LR junk in the gas tube. I am sure, in theory, you could clog a gas block. However, even after a brick of rimfire shooting, I have never had an issue.
Dedicated .22 LR Barrel CMMG Kit
The other CMMG kit is designed to work with a dedicated upper receiver built around a .22 LR chambered barrel with a compatible CMMG barrel collar. Builders can use the litany of AR upper receivers and parts for the build plus a dedicated CMMG, Beyer, or other similar .22 LR AR-format barrel. Some builders strive for an identical specification upper to retain a similar feel. Quite a few companies make barrels to this spec including CMMG and the .22 LR Benz match-chambered lightweight Beyer barrels.
Essentially, the entire CMMG bolt, guide, spring, and carrier are all identical to the drop-in kits. However, instead of a .22 LR to .223 adapter, there is a collar adapter that is designed to snap on/off dedicated .22 LR chambered barrels via a snap ring. With a dedicated AR upper, and .22 LR barrel, the CMMG bolt carrier unit slips and snaps onto the barrel. It is easily removed for cleaning. Obviously, with a dedicated barrel, the accuracy is significantly better. My Beyer-barreled builds generally deliver sub 1/2-inch 25-yards groups, which is rather outstanding accuracy from any .22 LR.
Functioning & Feeding
As with pretty much any AR-15 .22 LR option, the magazines are CMMG or Black Dog compatible AR-15 .22 LR magazines. CMMG offers reliable magazines as does Black Dog, which provides a variety of color and capacity options as well as a highly regarded steel lip version that offers longer-term durability.
If you want accuracy, versus a simple trainer, then the dedicated upper is the way to do it. With the drop-in kits, 2–5 inches is the expected accuracy, but sometimes you get lucky. I found that my Feddersen match .223 build with a red dot just happens to deliver .75-inch, 25-yard groups with the SK Match rifle. However, several of my Faxon-barreled builds delivered .5-inch, 25-yard groups with CCI SV ammo.
Generally, the .22 LR rounds like a bit more smack from the hammer. The only issues I experienced were with very light match triggers. However, Rise, Hyperfire, Geissele, and Timney as well as most stock MIL-SPEC triggers have all worked well for me.
Beyer Barrels – For the dedicated upper builder, Beyers barrels are not just .22 LR AR-15 barrels, they are Benz match-chambered .22 LR barrels, featuring a threaded 7075 aluminum sleeve for a very lightweight build. Beyer has barrel models to support both 10-22 variants as well as AR-15 platforms and is compatible with CMMG collars.
These are extremely accurate barrels that regularly deliver sub-.5-inch 50-yard groups with rifle-length barrels. Even with my 4.5-inch, suppressed .22 LR AR Beyer build, I can easily hold under .5 inch at 50-yards, and it has been fantastically reliable. Currently, Beyer offers 4.5, 7.5, 9.5, and 16-inch .22 LR barrel lengths to support a variety of builds.
Training gets expensive. Some training can, and should, be with full power, centerfire rounds. However, when it gets into repetitive drills that are more about practicing muscle memory on steel or working though the mental and physical process of shooting around barricades, .22 LR is more than adequate and saves a ton of cash with every box of ammo. There is no better plinker than a .22 LR, and nothing cheaper. Around 700 rounds, the dedicated conversion pays for itself, which I consider a deal.