Remember back when .22LR was 6 cents per round and there were 20 bricks on your local gun shop’s shelf for $19.99? Prior to the great ammo drought of 2013, conversion kits were just picking up steam and hitting the market left and right, with perhaps the best of the bunch made by CMMG. Luckily I still have a stockpile of .22lr, so let’s forget about the ammo woes briefly and see just what a mid-tier .22 conversion brings to the table for AR-15 owners.
Charging handle not included on our test kit.
Overview
CMMG makes a series of .22LR conversion kits with various additional features, ranging from what used to be called the Alpha to India. The Alpha kit consists of only a conversion magazine and a phosphate coated .22LR bolt group, no addons. The Bravo unit, which is what ours is more or less, is stainless instead of plain phosphate but otherwise identical. As the phonetics increase, more features are added such as an anti-jam dedicated .22 charging handle, a bolt hold open trip that uses the standard BHO on the lower instead of the magazine follower, and a forward assist to give full AR-15 functionality.
A year or so ago, CMMG redesigned some aspects of their kits and the magazine was overhauled into the .22 ARC EVO series of kits, and our test kit is an EVO kit using the new very PMAG-esque conversion magazine instead of the old light grey USGI looking one. The new magazines are extremely sturdy and feed well once broken in a little, but we’ll get into that more later. All of the new kits are stainless and the Alpha was discontinued.
The test kit here is an EVO Bravo kit consisting of the bolt group and new style (R3) magazine and retails for between $200 and $229 with the latter being direct from CMMG’s online store. An upgraded version of the kit dubbed the Echo includes the forward assist adapter and anti-jam charging handle for $250-279.
Accessories sold by CMMG include all of the components of the higher priced kits such as the anti-jam charging handle, magazine loader, forward assist plate and bolt hold open actuator. Magazines retail at around $25 apiece and are available in 10 round pinned or 25 round capacities.
The bolt and charging handle after about 400 rounds.
Function and Reliability
Over the past couple of weeks, I shot the conversion kit in a test rifle using an inexpensive Palmetto PTAC mid-length 16″ barreled upper bolted to the FDE TN Arms lower I’ve been abusing. In total, the kit saw a mix of around 400 rounds of various branded .22LR including Federal Lightning, Winchester Wildcat and X-Pert, Remington Thunderbolt, PMC Sidewinder and probably others on top of that. Neither kit nor rifle were cleaned for the duration of the testing, and the dirty bolt is shown above.
The first concern was that the magazines don’t appear to drop free in some receivers, but do in others. They’re just a tiny bit snug in the TN Arms (gen 3) receiver, drop free just fine in the New Frontier lower, but don’t fit whatsoever in the Surplus Arms lowers I have on hand. I think that says more about the SAA lowers than it does the magazines, but the combination of a tight magwell and the conversion mag doesn’t work out well. Just note that results may vary between receivers, because the magazines are on the bulky side and could require a little bit of shaving.
Speaking of conversion mags, while the new R3 mags are excellent in build quality and extremely sturdy they take some breaking in. In every range outing the first couple of rounds from the fully loaded 25-round magazine failed to feed by stubbing on the feed ramp. Once you’ve fired off those couple of stubs the kit feeds very well. Overall reliability was good but far from perfect, and I experienced several stovepipes about once per magazine. During testing I also encountered two rather amusing stoppages that you don’t see every day.
The first was that when clearing a stovepipe I made the mistake of treating the gun like a regular 5.56. Instead of exaggerating rolling the gun clockwise to dump out the empty, it slipped past the bolt group and into the lower receiver without my noticing which resulted in the hammer falling onto the spent casing!
Oh, that’s why it fails to fire.
The second was a stray casing finding its way into the channel inside the charging handle and the bolt closing on it half-open. I imagine that’s what the special .22 charging handle is for that CMMG sells with the higher kits, but I only experienced it once during my testing so I can’t really say the special charging handle is a necessity.
Ammo sensitivity does not appear to be a problem. None of the myriad of brands I threw at it seemed to cause feeding problems, even the notoriously stubborn Sidewinder which few semi-autos can feed reliably. I suspect that some of the stovepipes may have been due to the old, milder ammo. Federal Lightning and Winchester Wildcat both fed, fired, extracted and ejected very well. Plain lead or copper plated didn’t make a difference, and during the course of testing I mixed in some hollowpoints which fed just fine too.
Build Quality, Design and Cleaning
“Clean” is a good term to use to describe CMMG’s work on these kits. The machining is clean, the welds are clean, overall it’s just a well constructed kit that is at least in my opinion well worth the purchase price. The magazines are once again very sturdy and the polymer material seems on par with any quality AR magazine. There’s not a ton to say here, since it’s exactly what you would expect to get from a company like CMMG.
As you would expect from any .22 kit, it gets rather dirty. On the plus side, the stainless units are easy to clean and using certain gun care products can potentially repel more fouling for a quicker cleaning job. I was actually surprised the fouling wasn’t worse after a few hundred rounds, given the old dirty ammo I force fed the poor thing. The usual hotspots for dirt apply: the bolt face, chamber area and both the inside and outside of the chamber insert get noticeably dirty while the rest of the unit gets dusted at worst.
Test upper after lots of .22lr
Taking apart the bolt group for cleaning is very straightforward and extremely clever. The kit uses a guide plate that grabs onto the chamber insert by way of two arms, so simply spreading the arms apart slightly will allow you to pop the chamber insert out and carefully let the bolt itself forward. You don’t really need to take it down any further for normal cleaning, but do remember to swab out the chamber insert’s “bore” while you’re at it.
Guide plate tabs shown spread apart to disassemble.
For a full detail strip, the firing pin is removed similar to a normal AR-15 bolt by way of a cotter pin retaining it. Be warned that unlike an AR-15, the firing pin is spring loaded here! The extractor is retained by a pivot pin that can be driven out from the top to the bottom, once the bolt body is removed from the guide plate. Otherwise the guide plate’s rail blocks the hole and serves as a second retainer for the pin to make sure it won’t walk off.
The kit broken down into its major assemblies.
Concerns and Summary
I like the design overall but do have two concerns to bring up for anyone interested in gunsmith-babble. The first is simply that the feed ramp, while cleanly machined, is somewhat rough and could do with some polish. That’s not unusual at all in the gun world these days and is something anyone can fix at home with some elbow grease. The other concern is that the extractor seems to have mediocre spring pressure, again a fairly minor concern that could be fixed if it became a problem. Extractor tension, particularly on rimfires, can be overdone and cause even more problems so I don’t recommend anyone go stretching the spring or replacing it unless you’re getting a lot of dropped cases.
Pros:
- Reasonably priced
- Excellent build quality overall
- New all stainless units are simple to disassemble, easy to clean
- Myriad of addons and extras to add functionality
- Doesn’t seem to be ammo sensitive
- Solid design that performs well overall
Cons:
- Expect stovepipes once in a while, it’s not perfect
- Magazine fit is a problem on some lowers
- Won’t get full AR-15 functionality without addons
The Bottom Line: A good buy for anyone who owns an AR-15, in my opinion. If .22LR ever gets back to what we’ve all come to know as normal, one of these kits should be in every AR owner’s gun safe!