PSA: SAAMI’s Guide to Unsafe Gun-Ammo Combinations

It should go without saying to never use ammunition in your firearm that is not written on the side of the firearm… Well, except in cases like .223 and 5.56, where the two are semi-interchangeable, or in the case of .38 and .357, where one is compatible with the other, but not vice-versa. So “feed a gun only ammo it’s chambered for” is a good handy rule of thumb, but as always things are just a little bit more complicated than that. There are a whole host of resources available on the internet talking about ammunition-chamber compatibility, but one thing that isn’t as thoroughly discussed – for obvious reasons – is the bad combinations. Fortunately, the Sporting Arms and Ammunition Manufacturer’s Institute, better known as SAAMI, publishes a document annually covering some of the worst common ammo-firearms combinations which should be avoided in all circumstances. The document is hyperlinked above for reading at your leisure, and below is what SAAMI says about the list:

The discharge of ammunition in a firearm that is not designed to shoot that ammunition can be dangerous and can result in serious injury or death to the user and/or bystanders, as well as damage to the firearm. This unsafe condition is caused by an excessive build-up and/or release of high-pressure gas in a firearm’s chamber, barrel and/or action beyond which the firearm is designed to withstand. Therefore, in the interest of safety, you should use only ammunition of the caliber or gauge designated by the firearm manufacturer for use in that firearm. Markings indicating the correct caliber or gauge of ammunition to be used in a firearm are usually found on the firearm’s barrel, frame or receiver

One way to verify that you are using the correct ammunition is to check the head stamp on the ammunition to confirm that it matches the caliber or gauge markings placed on the firearm by the firearm’s manufacturer. Some types of ammunition do not have markings on the head stamp of the cartridge. In that case, check the original ammunition packaging to determine its caliber. If you have any doubt about the caliber of the ammunition, you should not use the ammunition until you have it examined by a qualified person who can determine its caliber. Remember just because a round of ammunition can fit into a firearm’s chamber, barrel or action does not mean it is safe to use that ammunition in the firearm.

Due to the availability of many different shapes and sizes of ammunition and firearms, there are countless unsafe ammunition-firearm combinations such that a comprehensive list of unsafe combinations is neither feasible, nor practicable. Below is a list of some unsafe combinations that are well known because of somewhat similar chamber and ammunition dimensions.

If the caliber or gauge is not clearly marked on the firearm, or if it appears the original markings on the firearm have been altered or modified in any way, do not use the firearm as serious injury or death could result to the user and/or bystanders, as well as damage to the firearm.

Similarly, SAAMI has not published voluntary recommended practices or procedures for re-chambering of firearms. It is possible the re-chambering of a firearm may not have been done properly or may not have been properly marked on the firearm. If the caliber or gauge marking is missing or altered in any way, you should not use the firearm. You should instead have the firearm examined by a qualified person to determine what caliber or gauge ammunition can safely be used in that firearm.

Stay safe, folks!

H/T, ammocollectorME on the IAA Forum.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • ostiariusalpha

    Ermahgerd. I understand why most of these rounds require this attention, but you know some of those cartridges are on this list only because people managed to cram them in into the chamber by force. A warning won’t cure stupid.

  • eriky

    I like the whole idea behind this list but some are bordering on DUH!
    40S&W in a 9×19? If someone is using a mallet to chamber a round this list isn’t gonna help them either XD

    • Giolli Joker

      45WM in 45ACP or 45GAP, or 44Mag in 45ACP would require some effort or “out of the box thinking” as well…
      Curiously .460 Rowland is not mentioned.

    • Cal S.

      But it’s just 1mm bigger, right?

      I have read a story, I think it was on here, about an ammo mix-up that led to 9mm being shot from a .40S&W thanks to Glock’s interchangeable mags. No kabooms, but it resulted in some interestingly necked cartridges…

      • Giolli Joker

        Yep, but that is the opposite. Loading a .40 in a 9mm would require hell of a loose chamber…
        Unless you can get out of battery discharge on some 9mm open bolt guns by loading a .40 round…

        • Cal S.

          Yeah, that was meant to be a poking remark, probably understood better with a pot-head accent. I do know you’re not supposed to put larger boolits in smaller guns.

    • Sulaco

      But I have seen 9mm chambered and fired in a .40 S+W with out damage to the gun but the case split…

      • TonysTake

        <<– is just shaking his head. Just because you can, sure doesn't mean you should.

        • Sulaco

          Ammo mix up not on purpose…another reason to keep close watch on ammo on the range.

    • Zachary marrs

      I saw a guy cram a 7.62×39 into his mini 14 once

      You’d be suprised how strong stupid can be

  • cs

    Did they forget about the judge, governor, and a host of other breach shotguns when they posted:

    In Shotgun Chambered For Do Not Use These Centerfire Metallic Cartridges:
    Bore Any

    • Giolli Joker

      Those revolvers are specifically chambered to fire both 45LC and 410 gauge… normal 410 shotguns aren’t, hence the warning.

      • Phil White TFB Contributor


  • Bear The Grizzly

    What I find most ironic about this is that the people who are most likely to do something that stupid would never read this information or even put it to use if they did.

  • Giolli Joker

    I would add .44Mag in .50AE, not impossible to happen in a Desert Eagle, it just takes using the wrong magazine…

  • me

    What about .50 BMG in a 12 gauge?

    • TonysTake

      How about an RPG in a .22?

  • UCSPanther

    In 12 gauge shotguns: 3 inch shells in 2 3/4 inch chambers is another common invitation for disaster. The 3 inch shells fit, but when fired, they partially obstruct the bore and lead to a dangerous spike in pressure.

    Many people have been maimed, and countless shotguns destroyed by that mistake…

    • slippery pete

      Think of all of the Pals injured by you worthless IDF f#cks

      • UCSPanther

        There are old pictures from WWII of oh-so-tough “Aryan Ubermensch” murdering unarmed civilians. You National Socialist worshippers are damned hypocrites.

        • Phil White TFB Contributor

          “Was there any form of filth or profligacy, particularly in cultural life, without at least one j## involved? If you cut even cautiously into such an abscess, you found, like a maggot in a rotting body, often dazzled by a sudden light – a k!k# !”- AH in Me#n Kam#f.

          • UCSPanther

            I’m sure your fake account is appreciated.

            I also suggest you find some different reading material than a two-bit manifesto written by a failure of a dictator who put a .32 slug into his head…

          • Phil White TFB Contributor

            Then why are you heeebs so obsessed with him? I mean, my God, every other movie out of Hymiewood’s garbage factory is about him.Spielberger has made billions from the hollowhoax myth alone. j##ish men hire Aryan studs to dress up like SS officers to f##k their wives while they watch.

          • UCSPanther

            First you deny the Holocaust, then you scream “Six Million More!”

            Make up your mind, loser. And it is freaks like you who are obsessed with that long defeated regime, still raging over the outcome of a cataclysmic world event that was settled 70 years ago and counting.

            Your ideology has lost. It is kaput, finished, defeated. The only people who admire that dead dictator are failures at life like yourself, who sit in your basements and whine about how hard done by you are by some imaginary cabal.

            I also detect a little bit of sexual frustration in your rant…

          • Phil White TFB Contributor

            over? no, the whispers that are heard just means it’s beginning again.

          • UCSPanther

            That’s what you have been saying for years, and National Socialism is no further ahead than it was at the end of WWII.

            A pack of basement dwellers, failures at life, drug addicts, edgy teens and bitter old men does not a Reich make…

          • UCSPanther

            And seriously, you need to get a life, stop hanging out at cesspools like the Daily Slave, and fix your attitude.

            You are not going to go far in life as a raving bigot…

          • He’s a loser. He’s just aggravated he can’t make me mad:-)

          • Yea best thing is just ignore him until I see his post and ban him again.
            No audience no reaction from any of us would be boring for the poor lost soul–LOL!

          • UCSPanther

            This idiot has been stalking me, so I fixed my comment history so he can’t follow me very easily.

            I guess to run with the trash who frequent the online sewers that he seems to hang out at (Daily Slave is one of them), one has to be really stupid or mentally ill.

            I just love how he tried to impersonate you. The grade on his attempt: Epic fail.

            Hopefully, his fun will be spoiled and he will be forced to remain in the cesspools that he loiters in. I apologize for inadvertently bringing that vermin with me.

          • No problem and it’s sure not your fault. He really is a lost soul as are those like him. What a way to waste a life.

          • LOL—- he really is to be pitied.

  • Southpaw89

    On a side note many old military rifles don’t have caliber markings on them, or have an incomplete marking, (I think my Carcano only says 6.5, which could cause confusion with other 6.5s) Usually careful research can tell you the appropriate caliber, but if its been sporterized you can never really be sure. I’m sure most people here don’t need to hear this, but it would be good for folk just getting into surplus firearms to know.

    • If you can’t find any caliber markings on a firearm, or they are ambiguous, take it to a gunsmith. If worst comes to worst, he should be able to cast the chamber and determine the caliber for sure.

    • Cameron Bissell

      True I’ve seen some oddballs bored out or necked up like 6.5 roberts and others.

  • Will P.

    I’m just trying to figure out what the cover picture is? Is that a 300BLK stuck in a 5.56mm chamber/barrel?

  • Cliff notes: Don’t use a caliber other than what is marked on the weapon.

    90% of the warnings are things that won’t work. For example under 9mm you have 40S&W, if your 9mm gun can chamber a 40S&W it might be time to visit a gun smith.

    • Zachary marrs

      What if you have a Taurus?

  • Ultra-squeezebore! Only fires once!

    • ostiariusalpha

      Now you’ve got me imagining someone loading up their Blackout brass with duplex M198. For science!

      • And they chrono it and get… Ten feet per second! 😉

  • Secundius

    Well I know the Kel-Tec PMR-30 in .22WMR, will chamber the .22TCM and the 5.7x28FN in Spitzer’s. The M1903 in .30-03 to .30-06. The .308Win to 7.62x51NATO, but not Vice/Versa. And the 98k Mauser in 7.92×57 to 8x60S, 6.5x55Swede, .303British…

    • Slvrwrx

      Say what? A .22TCM round will definitely not chamber in a PMR-30 and neither with the 5.7 round.

      • Secundius

        @ Slvrwxr.

        The 5.7FN was a mistake, its suppose to be 5,7x28FN can chamber either the .22WMR or the .22TCM, but in Spitzer’s only.
        The .22WMR or .224-caliber/5.7×34.4mm w/an oal of 34.4mm and .22TCM or .224-caliber/5.7×32.1mm w/an oal of 32.1mm. I’ve had this discussion before on other website like The Shooter’s Log…

        • Slvrwrx

          The .22WMR “would” go into a 5.7x28mm chamber, because the case diameter is about .242″, compared to the .312″ of the 5.7. However the .22 TCM would not even come close. It has a case diameter of .370″. It’s a fat little cartridge. Now a 4.6x30mm HK round “would” go into the 5.7 chamber.

          • Secundius

            @ Slvrwrx.

            Fine, do what you want Sir. I have friends who have switch from .22WMR’s to .22TCM’s because they like the Performance Characteristics better in the TCM’s…

          • Slvrwrx

            There’s no doubt about that. The .22TCM is 2000 fps from a 5″ barrel. You’re lucky to get 1400 fps from a .22WMR in a 5″ barrel. I was merely stating that you’d need to be a magician to chamber these rounds in the wrong guns..

  • TechnoTriticale

    There’s a substantial inconsistency in the SAAMI chart between what not to use in 5.56×45 and what not to use in .223 Rem., with 300BLK being ominously absent from the 5.56 list. 300 BLK is perhaps the #1 range hazard today.

    There are others missing entirely, like .38 Long Colt, which will chamber and fire various .38 rimmed cartridges (once, anyway). Most .38 SPL loads are severe damage risks in 38LC revolvers. .357 MAG is an almost assured kaboom.

    And why not list 9mm Largo in the left column under .38 ACP. Largo Llamas, for example, will chamber and fire .38 Super, with no-so-super consequences.

    8mm Lebel? Well, let’s just say that the list is far from comprehensive.

    • Biggest range hazard is dummies with no muzzle discipline, but I agree with you that the .300 Blackout presents a bit of a hazard around .223 chambers.

  • faex

    I find it odd that they say do not fire 9mm NATO in a 9mm Luger (Parabellum) pistol. I do that at least once a year with my military issue M9 Beretta.

    • Paladin

      If your Beretta is military issue then it almost certainly has a NATO spec chamber, not the 9mm Luger SAAMI spec. NATO specs allow for higher chamber pressure than SAAMI specs do (36,500PSI vs 34,100), so there’s no problem firing SAAMI spec ammo in a NATO chamber.

      In addition, firearms rated for 9mm Luger +p should also be safe with 9mm NATO ammunition, as the upper limit on +p loads is 38,500PSI.

    • That has a 9mm NATO chamber, as do most modern pistols targeting the military market.

    • iksnilol

      9mm Luger is usually used to refer to weaker loadings of 9×19. Weaker loadings suited for the old milsurp guns.

  • Tassiebush

    A few I can think of are 2-3/4 12gauge used in old 2-1/2 12gauge and then there’s the 20gauge shell mixed in with 12gauge that can slide down in front of chamber leaving enough room for a 12gauge cartridge (20gauge shells are yellow to help avoid this).
    Another is stray 8mm Mauser mixed with 3006 ammo.

  • TonysTake

    NEVER EVER, EVER run 5.56 in a rifle chambered for .223 unless you like exploding guns. READ THE INSTRUCTIONS! You can shoot .223 all day long in an AR-15 chambered in 5.56, but not the other way around. It is like the .38 and the .357. One way works. The other way doesn’t.

    • It’s actually not very much like .38 and .357 at all. For one thing, .357 doesn’t physically fit in a .38 cylinder.

      • TonysTake

        Don’t give people the wrong idea. Just because it fits doesn’t mean it’s O.K. I have seen two Colts chambered in .223 turned into pieces of junk because the 5.56 “physically fit.” These two guys were very lucky they only lost the $600 and not an eye or a hand. It is undoubtedly the most dangerous combination out there today for the simple reason there are so many of them in the hands of first time shooters.

        • It can be a problem with certain chambers, but as the article above explains quite thoroughly, it’s quite a bit more complicated than that.

    • iksnilol

      If it is American guns, then true. Though for European guns it is a bit different. Here in Europe .223 is rated for the same pressure as 5.56. So for instance Saigas stamped with .223 are perfectly safe to shoot with 5.56. While ARs or Mini-14s stamped with .223 aren’t.

      • Yep. CIP spec is different than SAAMI spec. That’s the thing, is it’s not really “5.56 vs. .223”; it’s 5.56 (lots of subdivisions of this), .223 Remington (SAAMI), .223 (CIP), .223 Wylde, 5.56 Noveske, etc, etc, etc ad nauseam. All of these different kinds have tolerances meaning no two chambers are alike, meaning all you can really do is check your brass for overpressure signs and be careful.

        Or buy a 5.56 spec chamber.

        • iksnilol

          No matter what you’re using, even if it is correct ammo and chamber you should still keep an eye on your brass.

          .223 Wylde seems good, if you can get one that’s properly made. .223 Noveske is also good, + since only Noveske makes it you are guaranteed a good barrel with that chamber.

  • Goody

    Besides the latest hot-rod F-Class cartridge, what do you think is the story in the picture?

    • Marcus D.

      It’s posted above. 300 blackout in a 5.56

  • Jim

    Might mention that you can use BOTH .223 AND 5.56 ammo in .223. Wilde but you should NOT use 5.56 ammo in a firearm designated just .223.

  • Kivaari

    A weird example is a friend used a .270 Win in a 7mm Rem. Mag., he spotted a deer close by. He took the shot, and there was the usual brown smoke coming out of the action and the deer ran 75 yards and dropped. He worked the action only to find a case split open and expanded. As he dressed the deer ha found the bullet. It had hit the deer sideways and bent into a shallow “U”. I don’t recommend it.

  • jeff k

    what about .223 wylde it shoots bot .556 and .223

  • J S

    I wish manufacturers would document this clearly also.
    As an example, RIA, in the manual for the 22TCM 1911, calls for using .22TCM FMJ rounds, or it will void the warranty. Those rounds are NOT available to the public as they are consider armor defeating.