PSA: Shooting .22 Long Rifle in .22 Magnum Cylinders

A recent article in a popular gun magazine repeated a common—but dangerous—misunderstanding, and reminded me that you can’t always believe what you read.

The article was a review of the North American Arms (NAA) True Black Widow—a single-action, “mini-revolver” chambered for the .22 Winchester Magnum Rimfire (WMR), or “.22 Magnum,” as it’s more commonly known.

In the review, the author proposed that shooters who were concerned about the cost of .22 Magnum ammunition could shoot the more economical .22 Long Rifle (LR) in the gun1. Unfortunately, this is not only incorrect, it’s also very dangerous! So, in the interest of safety, your RevolverGuy team would like to remind you that the only ammunition which should be loaded and fired in a .22 Magnum chamber is the .22 Magnum2. It is NOT safe to shoot .22 LR in a .22 Magnum chamber!

North American Arms clearly states that it’s not safe to shoot .22 LR in the .22 WMR chamber. RTFM!


Unlike the relationship between the .38 Special and the original Magnum handgun round—the .357 Magnum—the .22 Winchester Magnum Rimfire (WMR) is not simply a stretched version of the earlier .22 LR cartridge. It’s safe to shoot the .38 Special in a .357 Magnum chamber because the two cartridges share nearly identical dimensions, outside of a small variation in rim thickness and a larger difference in overall case length (designed to prevent the .357 from fitting in .38 Special chambers).

.22 LR Specifications, from the Ammo Encyclopedia, 3rd Edition—See footnote 3, below

This is not the case with the .22 LR and WMR. The WMR case is larger in every dimension, compared to the tiny LR case. It’s longer, has a thicker rim, is wider, and has a larger case head. The WMR cartridge was designed to fully enclose a full diameter bullet, rather than merely grip the reduced diameter heel of the bullet, as in the LR.

.22 WMR Specifications, from the Ammo Encyclopedia, 3rd Edition—See footnote 3, below

Therefore, if you place a .22 LR in a .22 WMR chamber, it will be a sloppy fit. If the LR cartridge is actually fired in the WMR chamber, the case may rupture and vent high pressure gases and particulates rearward, through the breechface. There is a significant risk of injury if you fire .22 LR ammunition in a .22 WMR chamber!

You can easily see how the smaller .22 LR case head (on right, at 5 O’Clock position) fits sloppily in the .22 WMR cylinder, compared to the .22 WMR (on left, at 7 O’Clock position)

What about my Convertible?

About now, some of you are wondering about the popular “convertibles,” like the excellent Ruger Single Six, which come equipped with a replacement cylinder that allows you to shoot .22 Magnum in a gun that is nominally designed as a .22 Long Rifle.

Shooting .22 Long Rifle in a gun like the Ruger Single Six is entirely safe, provided you are using the supplied .22 Long Rifle cylinder. The .22 LR cylinder has chambers that are cut for the dimensions of the .22 LR case, so there is no safety concern here.

Match the ammo to the proper cylinder and you won’t have any issues with your Single Six or other convertible .22 revolver.

However, it is obviously NOT safe to shoot .22 LR in the .22 Magnum cylinder supplied with the gun, for the reasons explained above. Shoot all the Magnums you want in the Magnum cylinder, but leave the Long Rifles for the .22 LR cylinder, please!

Incidentally, the SAAMI spec for .22 WMR bore and groove diameter (0.219” and 0.224”, respectively) is larger than that for the .22 LR bore and groove diameter (0.217” and 0.222”, respectively). Therefore, manufacturers like Ruger have to drill and rifle the barrel for the slightly larger WMR spec. This should really have little practical effect on  LR bullet accuracy, but it makes for fun conversation around the campfire.

Caveat Emptor

So, there are two important takeaways here. First, never fire a .22 LR cartridge in a .22 WMR chamber! Doing so places you and others at risk of injury, and will also lead to ruptured cases in your gun that will be more difficult to clear.

Keep ‘em straight!

Second, be cautious about where you get your firearms information, and try to verify with another source. All of us writers make mistakes sometimes, and what we meant to say isn’t always how it comes out on paper. We hold ourselves to high standards here at RevolverGuy, and always endeavor to provide accurate information—even if it’s unfavorable to a product or manufacturer—but we’re human too, and can make mistakes. Don’t treat our word—or anybody else’s in this business—as gospel. Do your own homework, especially if something doesn’t sound right.

Shoot straight and be safe out there!

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1. From the article: “If you want cheaper practice, you can stuff .22 Long Rifles into the cylinder, a bit like using .38 Specials in a .357 Magnum;”

2. Technically, the (near obsolete) .22 Winchester Rim Fire (WRF) can be safely fired in some .22 WMR chambers, because the two cartridges share many identical case dimensions. However, industry icon—and all-around ammunition authority—Michael Bussard advises the WRF should not be fired in revolvers chambered for the WMR;

3. Cartridge specifications from the Ammo Encyclopedia, 3rd Edition, by Michael Bussard. 2011. Blue Book Publications, Minneapolis, MN.  RevolverGuys are highly encouraged to purchase this excellent and highly educational resource!




Author: Mike

Lieutenant Colonel (Ret.) Mike Wood is a bonafide revolver nut, a certified law enforcement instructor in handgun, shotgun, patrol rifle, less-lethal, and diversionary device disciplines, and the author of Newhall Shooting: A Tactical Analysis, the definitive study of the infamous, 1970 California Highway Patrol shootout in Newhall, California. Mike wrote the "Tactical Analysis" column at for 8 years, and enjoys teaching both armed citizens and law enforcement officers.

25 thoughts on “PSA: Shooting .22 Long Rifle in .22 Magnum Cylinders”

  1. In his excellent book about firelapping, Marshall Stanton of Beartooth Bullets says that because there are no subsonic loads for the WMR, it is permissible and safe to fire properly treated .22 Long rifle cartridges in .22 Magnum cylinders. FOR FIRELAPPING ONLY! .22 CB rounds are suggested, giving “airgun velocities”, and you can knock the swollen Long Rifle brass loose with a cleaning rod. Peersonally, I’d rather not! Good article!

  2. I was hoping that the author of the other article was reviewing a conversion model (with the .22 LR cylinder) and just failed to clarify, but no; I double checked, and the True Black Widow (or NAA-BWM-PVD) does not come in a conversion set at this time. Yikes.

    I’m not familiar with the Ammo Encyclopedia (but clearly should become so). How does it compare to Cartridges of the World?

    1. Yeah, that was the first thing I thought, but even in the review itself, the author clearly states it’s only offered in .22 Mag . . . so he knew it, and made the suggestion to shoot LR anyhow.

      Consider your sources carefully.

      1. Kind of an interesting suggestion anyway…this doesn’t seem to be the type of gun that is gonna get thousands of rounds put through it. I doubt most of these will have more than a box or two put through ’em.

        1. Not necessarily true. As an owner of 2 NAA revolvers, I can tell you they are fun to shoot. If not for the awkward way to reload them by having to remove the cylinder, they would absolutely be shot more! Almost every time I bring that gun to the range, someone asks to shoot it. And as far as my family, they seem to enjoy shooting it as well. But then again, this is just the opinion of 1 guy who happens to own 2 of their excellent revolvers.

      2. FYI, North American Arms supplies the .22lr with SOME of their magnum models, not all come with it. I have their excellent .22 mag. Pug. What North American Arms does do, is to offer their conversion cylinder as an aftermarket item. For ALL of there .22 magnum models. It’s basically an order, and then sending your revolver back to them for them to make sure the timing is correct and a charge I believe for 65 dollars. So yes, not all NAA revolvers come with the extra cylinder, but all are available for the conversion cylinder.

  3. My first revawver is a Single Six, with both cylinders. Have had it for ~45 years. Early on, I thought the .38/.357 and .22LR/.22Mag correlation was accurate. Tried LR’s in the Mag cylinder a few times; didn’t get hurt or have any blown cases, but the LR wouldn’t hit within minute-of-rabbit at common hunting distances. Shot lotsa Mag ammo at squirrels n’ rabbits n’ sich, killed them dead (the ones I didn’t miss). Shot lotsa LR ammo at the same critters, killed them just as dead–and didn’t hurt my ears as much. So the smart part of my brain convinced me to generally use the LR most of the time (for some reason, it really likes the Remington SubSonic in the accuracy department). Magnums are for those times I just want to ‘because’, or maybe if we’re anticipating tougher animals like coons n’ badgers n’ sich.
    Main point being, I’m glad that my experience with using improper ammo never drew blood (well, mine, anyway) or damaged my gun. Ace

  4. Yikes! I’ve know that you can’t shoot .22 LR in a .22 Mag since I was a little kid. It’s interesting that anyone would put info out that you can. Scary interesting! Nice job Mike! I wear eye protection all the time, but even at arms length a .22 LR in a .22 Mag can blow back enough explosive crud to injure someone’s eye.

  5. I can’t believe this is even a discussion. Only an idiot would shoot or tell someone it is safe to shoot .22lr in a .22 magnum cylinder. Obviously this is proof that there are some who shouldn’t have firearms or write articles concerning firearms.

    1. Mike,
      It is a shame that author put that in without researching first, and it’s even more of a shame that the article made it through editorial review. However, everyone is ignorant on something, none of us was born knowing this stuff, and all of us make mistakes.

  6. While I have known this is a “no no” for years, I have never seen such a clear and succinct explanation. Thank you Sir! I can now easily explain this to others and not just say “don’t do it”.

  7. Being the dummy I am I shot a few .22 in a .22 mag cylinder just the other day. It was the winchester .22 shotshells. They basically just underperformed greatly and the shells split apart inside the chamber so they needed more force to eject them.

  8. One’s life is priceless. Guns are expensive. A box of .22 mag, a round I just love for shooting varmints, can be had for as little as $9.99.

    The cheapskate pays the most, as the old saying goes. Get a Single Six and life is good. That gun shoots so well for me that its owner got angry!

  9. Ahhh… but there are sub caliber inserts. I’ve fired hundreds of 22 LR in my 22 mags with these.They look/ are 22 mag cases drilled out from the base and a slit cut on each side.Never had a problem even in a airlite 351pd.

  10. We have three North American Arms Black Widow Conversion sets in our household. Each came with two cylinders. I wasn’t aware they came any other way! They were all purchased in the 1990’s.

  11. In 1974 (or thereabouts) a college classmate of mine borrowed another classmate’s single six and away we went out into the desert to shoot some saguaros.
    Blazing away with 22lrs. we both were being pelted by lead and brass fragments. The empties were sticking in the cylinder, and the gun was jamming with bits of debris. Both of us knew-it-all, so both of us were trying to un-jam the gun -at the same time.
    Sure enough, it “just went off”. The bullet went into the fender of his Datsun, into the tire, and ricocheted off the rim and into Bill’s shin. The bullet fragments barely broke the skin and he only punched me once.

    We never even figured out that the 22 magnum cylinder was the culprit until we recounted the tale to the gun’s rightful owner.

    Later that evening Bill and I were engaged in a rousing game of darts. After several Blatz long-necks, I managed to miss the dartboard and somehow stabbed Bill in the same leg with a dart.

    William C. Williams, if you happen upon this bit of history, I’m sure you have never forgotten this event . . .


  12. What about shooting 22 long rifles in a 22 magnum Derringer where the barrel is actually the chamber how safe is thatMy friend has one and says that he can do this safely I’m just curious

  13. Is it just me or does anybody else see the irony or possible stupidity of a manufacturer calling its Long Rifle Ammo “Mini-Mag”? Why? To me it’s just another way for a mistake to happen. I know, I know, anybody with half a brain can easily see the difference when they open the box; but once it’s sitting in front of some cheapskate and he has already paid the money. It’s just, there is no real justifiable reason to call a long rifle cartridge “mag” or “mini magnum”, especially with this problem out there. And with all the Gun control nuts just salivating for a good reason to have to justify lawsuits for manufacturers!

    1. I can definitely see where it could lead an uneducated buyer down the wrong path. I’m sure that the Marketing guys thought it was a good idea, to promote the idea of increased power.

  14. Thank you for the article and all of the personal remarks. Having just acquired a Taurus .22 Mag. was checking to see if i could use a LR in the Mag. and learned all that i needed to know. Thank you Bernie

  15. I’ve accidentally put a few cylinders of .22lr through a .22 mag revolver. (Thought it had the LR cylinder in) There were no ill effects.

    I would not suggest doing so or make a practice of it though. Probably be shaving bullets on the forcing cone and busting cases semi often.

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