Question Of The Day: .22 Upper or Drop-In Kit?

We all love to shoot our ARs, AKs, SCARs and other modern sporting rifles ™, but the price of ammo makes it impossible to spend an afternoon burning powder without burning a hefty wad of cash in the process. Even if you don’t mind using the cheap (steel-cased) stuff, you have to plan for spending almost $75 to burn through ten 30-round magazines.

So whaddya gonna do?

You’re gonna find a way to play and practice using .22 long rifle, that’s what. It’s really hard to beat the .22 long rifle cartridge when it comes to price and availability. It doesn’t perforate Tangos as energetically as the 5.56 and it’s not as cheap as it used to be, but there’s no better bang for your buck in the shooting world. (Airgun pellets may be cheaper than .22 shells, but they don’t go bang so they don’t count in my book.)

If you get the rimfire jones for your AK, SCAR or HK, you’re gonna have to buy a whole new rifle for $300 and up. Luckily, AR owners have options that other shooters lack: we can pull our pins and install a dedicated .22 long rifle upper receiver, or pull the bolt and drop in a .22 long rifle conversion kit. Each option has its benefits and its drawbacks.

Dedicated .22 uppers are the more expensive option, for several reasons. First is the price of the uppers themselves: you’re lucky to find one for less than $350. The cost of these uppers continues to amaze me, since they’re only slightly cheaper than many quality centerfire uppers in 5.56 and other calibers. In fact, a dedicated .22 long rifle upper receiver group is nearly as expensive as a dedicated .22 long rifle AR rifle. What is up with that? I’ve never heard anyone gripe about their M&P 15-22, so I’d probably go that route before I went with a dedicated .22 upper again.

Whether you’ve got a .22 AR rifle or a dedicated .22 upper, if you want it to run like your ‘real’ 5.56 AR you’ll have to mimic your accessories like optics, lights, lasers and rails. There’s nothing wrong with substituting lower-priced alternatives on your .22 upper; nobody will call bullshit on you if you bolt a Chinese knockoff on your .22 instead of an Aimpoint Micro with a Badger Ordnance mount. But even bottom-shelf lights, scopes and mounts can add another Benjamin or two to the cost of your ‘budget’ rimfire range toy.

A .22 conversion bolt is far cheaper to purchase at $150 or thereabouts, and it also won’t need any new accessories other than maybe some extra magazines.

If you think I’m starting to lean toward .22 conversion bolts you’re right, but price isn’t the only consideration to keep in mind.

So what’s the catch with .22 conversion bolts?

The first catch is that there is no catch. .22 rimfire AR magazines don’t engage the bolt hold-open catch on mil-spec lower receivers. This means that your .22 reload drills will be different from (and slower than) your 5.56 reload drills because you’ve got to rack the charging handle when you swap out empty magazines.

CMMG sells a $20 conversion part which purports to make the hold-open functional, at least when used with proprietary CMMG magazines. It gets mixed reviews on the gun boards, and I only have one proprietary CMMG magazine so I haven’t bothered with it.

Another catch, er, issue is that your 5.56 optics are not zeroed for .22 long rifle ballistics. At tin-can distances they might or might not coincide, but at 50 yards your .22 shots will probably be way off. It’s VERY important to mark your 5.56 zero so you can crank right back to it when your .22 shooting session is done.

There are two other issues that affect .22 conversion bolts, but not dedicated .22 uppers or rifles: accuracy and filth.

When you shoot .22 long rifles through a 5.56 upper, accuracy is affected by the 5.56’s slightly larger bore diameter and much faster rifling twist. The .22 long rifle has a bullet diameter of .222 inches, and most .22 long rifle bores are slightly smaller than that so the soft lead bullets will seal well. 5.56s use .223 inch bores, which are just slightly oversized for .22 long rifles. Rimfire .22s also use a 1 in 16″ rifling twist, while modern 5.56 barrels are either 1 in 9″ or 1 in 7.” These factors combine to produce non-olympic smallbore grade accuracy in AR uppers, but few of us will care when we’re gleefully putting rimfire double-taps into cardboard targets at 75 feet or less at three or four cents a shot.

.22 rimfires are also dirty-shooting cartridges, because their soft-lead bullets are lubricated with wax or grease. All .22s suffer from this, but ARs suffer even more because all that lead and lube sludges up the AR’s oversized, overtwisted barrels and gums up their gas tubes.

In practice this means that cleaning your 5.56 AR after a rimfire practice session will be exceptionally unpleasant. You can minimize this if you bring your 5.56 bolt assembly to the range with you and fire ten or thirty rounds of 5.56 through the rifle when you’re done shooting the .22s. The full-power 5.56 rounds blast some of the wax and lead out of the barrel, and they also blow the wax out of the gas tube. Don’t worry, the slight wax buildup in the 5.56 bolt is really easy to clean.

All in all I’ve been much happier with a .22 conversion bolt than I was with a dedicated upper. Now I just wish they’d make them for my 5.45mm and 5.56mm AKs…


  1. avatar Peter says:

    A drop in kit would probably be fine in an older 1:12 twist rifle but as you noted, in a modern 1:9 or 1:7 you would quickly gum up the grooves and turn your AR into a smooth bore musket.
    Adding a cheaper red dot to a dedicated upper or rifle does cost a bit of money but just keep telling yourself that you are SAVING money, 5 cents a pop vs 50+ cents adds up quickly.
    That’s my story and I’m sticking to it.

  2. avatar GS650G says:

    It would be nice if there was an option for the .308 version but that’s OK.

  3. avatar Peter says:

    I have a cmmg dedicated 22 upper and love it. It runs like a top for about 750 rounds before you have to clean out the charging handle groves and charging handle otherwise you start getting ftl’s. i bought 5 of the new evolution mags and love them. Nice and robust and metal feed lips. Takes forever to load 5 but such grin inducing fun! The only other downside is the my mega billet lower and trigger group gets super dirty and gritty from the 22 ammo…..not cmmgs fault. You have to take your triggers out about 4000 rds or it just gets too gritty.

  4. avatar Damon says:

    i don’t have either setup at the moment, i simply have an old .22 marlin(even has a scope, and my AR only has iron sights! ha!) but i’d love to get a conversion. i’m leaning towards a dedicated upper, simply because of the cleanliness factor. i fully expect that if i get a dedicated upper, it’ll end up with it’s own dedicated lower as well, at some point, but that’s ok. having two fully functional guns instead of one and an extra upper floating around sounds better anyway.

  5. avatar ChainsawWieldingManiac says:

    One slight advantage to the dedicated upper is that I believe it’s slightly shorter due to how the barrel is placed in the upper… at least for the CMMG.

    I have a dedicated .22LR 6.5″ AR-15 SBR, and I use the CMMG upper. I would not trade it for anything.

  6. avatar Urquattro says:

    Have a piston Noveske AR and the CMMG (india?) kit for a piston gun was $300. Awesome setup and would recommend.

  7. avatar avsb says:

    I have a dedicated AR22 that is set up exactly like my AR15. That way I can train and plink on the .22 with the same exact muscle movements that I would with my AR15. A ton of fun to shoot.

  8. avatar Sid says:

    I am currently searching for a dedicated upper. My reasoning:

    – the sights and optics will remain with the upper so there is no need to re-zero when switching back

    – accuracy is better when the barrel has the correct twist rate

    – cleanliness

  9. avatar Tim says:

    I’d rather get the dedicated .22 AR with a Chinese optic rather than the conversion bolt.

    The downsides of the conversion are enough to me to offset the price.

    S&W m&p-15 22 here I come

    1. avatar JoshinGA says:

      The M&P 15-22 is a very fun gun, and eats up any .22 you throw in it. Mine even cycled subsonic flawlessly, even though the manual specifically says not to use low powered stuff. It replicates the fire control system of most ARs, but you can shoot it at 2 cents a pop. A dedicated AR in .22 LR is worth the money IMHO.

      1. avatar EATENG says:

        I will second that. My primary rifle happens to be a S&W M&P15, so buying the M&P 15-22 as a trainer just made sense.

        1. avatar Fyrewerx says:

          Same here. With a price often around $379, its hard to justify a conversion of a .223/5.56.

      2. avatar Elciddoc says:

        Echoing here, but my m&p 15-22 is set up exactly like my 5.56. I go through any ammo I get my hands on, but it shoots the federal value pack most accurately. I usually start my range sessions with 30 rounds of 5.56 and see what seems to be off – trigger squeeze, sight picture, etc. Then switch to the .22 for 3-400 rounds and work drills for what I’m screwing up, and then finish up with 2 more magazines of 5.56. I am amazed how much my groupings improve by training with my .22, and by saving $100 every time I do this, the m&p 15-22 has paid for itself several times over.

        1. avatar JoshinGA says:

          Have you tried the Winchester M22 ammo? Its my personal favorite. It feeds reliably, minimal FTF (some duds are expected out of all rimfire ammo), and accurate to boot.

    2. I have an S&W 15-22. Really nice gun. I enjoy shooting it, and my grandchildren do as well. Haven’t yet put a red dot on it, but intend to.

  10. avatar Terry says:

    Just went the dedicated upper (CMMG) route due to Foghorn’s essential AR accessories post; am awaiting the bolt hold piece, because my club requires chambers to be open and locked with magazines detached before the line is declared clear. I reasoned that it was better to use the same lower with its Timeny trigger to duplicate the feel when training with .22lr

    1. avatar Chris Dumm says:

      Let me know how it works out. $20 isn’t an objectionable price to get the gun running exactly like a 5.56, as long as it works as advertised.

      1. avatar 40&2000 says:

        I have a dedicated CMMG upper w/the bolt hold modification. I had a lot of problems initially and had to modify (file)the adapter. It works perfectly when you manually latch it & release but even the newest CMMG Evolution mags don’t actuate the hold open reliably. In all fairness I never contacted CMMG about the problem. There customer service was phenomenal when I had a different problem.

      2. avatar Terry says:

        There are some wrinkles that crop up with the bolt hold-open assembly from CMMG. It turns out that next generation (“Evolution”) CMMG mags are required to work with the hold-open. The mag pictured above with the green follower is not the kind you need (the follower is black). These new mags are devilishly hard to find, being out of stock almost anywhere. I found 10-round mags at Bass Pro Shops for $38 each! However, they do work properly in a function test, and I’ll write back once I range test them.

  11. avatar Daniel says:

    I’m not going to put dirty lead in a high-end AR with an $1100+ upper. No way, no how. Shooting a nice AR on the cheap is gonna cost ya a nice barrel in the end. What I’m planning to do is build a .22 on the cheap, then give it the same rail system, stock, and grip as the higher-end M4 I have on my radar.

    1. avatar Chris Dumm says:

      In your shoes I’d do exactly as you suggest: I wouldn’t shoot .22 long rifle through a Noveske or JP or Wilson Combat AR either. If I could afford such guns, I could afford to protect my investment in them by only firing .22 long rifle through an M&P 15-22 or a Umarex Colt .22 sporter that I bought for that purpose.

      Cold-hammer forged, chrome lined barrels have a service life of at least 15,000 rounds of higher-pressure, higher-temperature, jacketed 5.56. No quantity of low-pressure, low-temperature, soft-lead .22s could ever damage such a barrel, but careless or overly-aggressive cleaning (to get all that soft lead out of the grooves) can ruin any barrel in a hurry.

  12. avatar Pascal says:

    ATI, HK and M&P 15-22 are all nice dedicated 22lrs.

    I have the stagarms 22lr conversion and I believe it to be the best of the bunch because you can use your Stag just like it is.

  13. avatar Accur81 says:

    I’m leaning towards the M&P 22, but it looks like there isn’t a perfect solution.
    I have a Umarex Smith and Wesson M&P clone BB gun which is relatively accurate out to 50 feet, and shoots non-toxic steel BBs.

  14. avatar Skyler says:

    I don’t see the value in either option.

    Shooting .22LR will do nothing to help you shoot your AR better. If you want to shoot .22LR, might as well buy a .22 rifle.

    1. avatar Charles5 says:

      I tend to agree with you. About the only thing I have found usefull about .22 conversion kits is practicing trigger pull, which I can do dry firing. But the different recoil and the flight path of the round, in my opinion, could develop bad habits. Plus, at the price of most converison kits, it doesn’t make much sense. At $200+ for a pistol conversion kit, I could buy a brand new pistol for around the same price. At $300 for a dedicated upper, I may as well buy a full rifle. Besides, my 10/22 is all the .22 rifle fun I could want.

    2. avatar Ken says:

      Respectful but big disagreement. I shoot a lot of 3-gun and do academy training. Practicing with my 15-22 has helped me and others immeasurably. Difference in recoil? Doesn’t make a bit of difference when the buzzer sounds. Different trajectory? Except for shots beyond 50 yards that makes absolutely no difference in that kind of shooting. Dry fire just as good for trigger control? Nope. First, you can only dry fire once and then have to cycle the gun manually. You can’t dry-fire your way through a practice 3-gun stage. All the other things that go with that, i.e., reloads, multiple shots, etc. The 22 AR definitely has value for training/practice. And, as has been said, you can shoot a pile of it much cheaper. Is it a substitute for the big guy? No. You still have to put trigger time on it as well. But you can work out a lot of issues with the 22 before going to 223. Heck yes. Here’s one vote for the rimfire as part of a practice routine for the centerfire.

      1. avatar 10mmBestmm says:

        Exactly this. A 22 copy is a superb training tool. You can’t get that from dry fire alone. Plus, why not? 22 is tremendously fun to plink with (and even more fun with a binary trigger).

  15. avatar Aron says:

    I’ve had no issues with my CMMG conversion (other than it doesn’t like Remington .22 for some reason, and I happen to have a bunch of it).

    Like Chris suggested, I’ve always ran the real stuff through it afterwards to not only clear out the debris from the .22 but to verify my optic and iron sights. Aside from that, I give it a good cleaning with Froglube anyway.

    As for realistic training, I think it’s a good option for practicing movements, threat engagement and sound basics of tactical shooting. For those that say it isn’t the same as shooting the 5.56mm, you’re right. That’s why you should train with the real stuff too, using the .22 option only to offset the cost, not to take the place of training with the real deal.

    Good article.

  16. avatar Sanchanim says:

    Given that the cost is half the price of a complete upper I could see spending the money. a dedicated 22 is also an option, sure more expensive, but as anyone of us can attend to, when you take the kids to the range, having a few 22’s is important.

  17. avatar Justice06RR says:

    My opinion is to buy a separate 22lr rifle altogether, like the Mossberg Tactical22 or M&P15-22. Save your pennies and for a little bit more than the 22 conversion you will have a completely separate 22lr AR-style rifle.

    Walmart had the Mossberg 22 for $227 (although they are hard to find). They had one in my local SuperWalmart and it sold in about 2days; I’m still waiting for them to restock it! Dick’s sporting goods sells them for $299 if you can find them in stock.

    1. avatar JoshinGA says:

      The 15-22 is well worth the money. Ive shot ~2500 rounds through it and can count the FTFs on both hands. It gives a reliable strike, and your failures will be reduced to the dud rounds in the ammo you’re using. It feeds reliably, even with low pressure rounds, which the pamphlet it comes with warns against using. All that and it replicates the fire control system of a AR15, so it serves as a good trainer.

      Plus, lets be honest with ourselves: most all of us have a disease, and you may as well feed the need and buy a whole new gun outright rather than get a conversion kit which is merely an accessory to a gun you already own.

      1. avatar LongBeach says:

        +1 on the disease comment. I’ve got one of the Mossberg 22’s, and while it looks sweet, NONE of it functions like an AR.

  18. avatar blake says:

    great article here is a video of my cmmg 22lr with a gemtech suppressor

  19. avatar Mike says:

    I got a .22lr dedicated upper with BCG and charging handle for $299. Went this way because I did not want the gum up issues and the accuracy of the dedicated upper is better (twist and diameter are for .22lr). It uses the CMMG BCG without the sleeve and the bolt stays open as long as the magazine is in place (it does close when you remove the magazine).
    I use iron sights and all of my uppers are fitted with the exact same sights.
    All in all I found it to be a much better option and more fun than the law allows to shoot!

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