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  • 223 vs 556 rounds

    My department mandates using 223 over 556, as did my old department. I was curious on why a lot of departments choose 223 over 556, when (correct me if Im wrong) 556 is designed with stricter tolerances due to military mandates. My gut says to prevent over penetration (although, not to sideline the question, an ex-military guy on my squad believes that the 300 blackout is better for LE needs)

  • #2
    No.

    .223 Remington and 5.56x45mm NATO are very similar. The chamber dimensions for .223 are a little tighter, so you can shoot .233 ammo out of a 5.56 chamber, but if you try shooting 5.56 ammo out of a .223 chamber, you may have problems.

    Also, the specs for 5.56 ammo allows for more horsepower (62,366 psi) than .223 ammo (55,114 psi).

    As far as it's ability to quickly and efficiently turn bad people into good people, that has a lot to do with the mechanism of injury of various .223 and 5.56 projectiles, which is highly dependent upon the velocity of the projectile.

    To arbitrarily claim that .300 Blackout is better, is a gross oversimplification, especially since horsepower increases with the square of velocity, and .300 Blackout ammo is slow.

    Last edited by OfficerDotCom; 03-04-2021, 05:15 AM.

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    • #3
      Well the ex military guy I spoke off does study ballistics and has a lot of expertise due to what he did in the military, Im paraphasing but his opinion was based on the ballstics of the 300 blkout and overpeneteation of targets. however I dont know much about the round

      My question reference 223 and 556, I know about the differences in the barrels, but the question is in reference to the actually ballistics of the round itself.

      Is the 223 better than the 556 in our field due to the fact that we are typically shooting short to mid ranges and overpentration through the target could cause injuries and damges behind the target? Or is it simply that 223 is cheaper then 556

      Im curious if, in our field as opposed to the military we are less tolerant of collateral damage, and Im wondering if thats the reason that departments choose 223 over 556

      Thise question is about the rounds only, not the barrels

      I hope I cleared my question up.

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      • #4
        Originally posted by atrugen View Post
        Well the ex military guy I spoke off does study ballistics and has a lot of expertise due to what he did in the military, Im paraphasing but his opinion was based on the ballstics of the 300 blkout and overpeneteation of targets. however I dont know much about the round

        My question reference 223 and 556, I know about the differences in the barrels, but the question is in reference to the actually ballistics of the round itself.

        Is the 223 better than the 556 in our field due to the fact that we are typically shooting short to mid ranges and overpentration through the target could cause injuries and damges behind the target? Or is it simply that 223 is cheaper then 556

        Im curious if, in our field as opposed to the military we are less tolerant of collateral damage, and Im wondering if thats the reason that departments choose 223 over 556

        Thise question is about the rounds only, not the barrels

        I hope I cleared my question up.
        As I said, it depends on the projectile and it's velocity, whether we're talking about the 40-grain JHP "Blitz", the 62-grain tungsten-core SS109 "green-tip" projectile in the M855 5.56x45mm NATO ammo, or the 77-grain OTM Sierra MatchKing in the Mk262 ammo.

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        • atrugen
          atrugen commented
          Editing a comment
          So the question still stands, why are alot of departments choosing to mandate the use of 223 over 556?

      • #5
        So the question still stands, why are alot of departments choosing to mandate the use of 223 over 556?
        Because departments might not technically be using 5.56-capable rifles. It's generally not recommended that 5.56 be fired from .223 rifles because of increased cartridge pressures (while 5.56-specced rifles can shoot .223). Departments frequently pick equipment on the lowest-cost principle, so departments purchase .223's (meaning common non-military AR's) if they're cheaper than their more rugged 5.56 brothers.
        "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you."
        -Friedrich Nietzsche

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        • #6
          [QUOTE=Bing_Oh;n6979286]

          Because departments might not technically be using 5.56-capable rifles. It's generally not recommended that 5.56 be fired from .223 rifles because of increased cartridge pressures (while 5.56-specced rifles can shoot .223). Departments frequently pick equipment on the lowest-cost principle, so departments purchase .223's (meaning common non-military AR's) if they're cheaper than their more rugged 5.56 brothers.[/QUOTE

          My old department issued 556 capable rifles, my new one has a use you own policy, and does have some issued rifles that are 556 capable.

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          • #7
            Originally posted by atrugen View Post

            My old department issued 556 capable rifles, my new one has a use you own policy, and does have some issued rifles that are 556 capable.
            Our department's G.O.s said that our ARs had to be capable of shooting .223 ammo, so that meant we could use 5.56x45mm NATO chambers, .223 Remington chambers, .223 Wylde chambers, or anything else compatible with .223 ammo...

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            • #8
              Originally posted by Bing_Oh View Post

              Because departments might not technically be using 5.56-capable rifles. It's generally not recommended that 5.56 be fired from .223 rifles because of increased cartridge pressures (while 5.56-specced rifles can shoot .223). Departments frequently pick equipment on the lowest-cost principle, so departments purchase .223's (meaning common non-military AR's) if they're cheaper than their more rugged 5.56 brothers.
              Even before the ammo shortage, my PD found it much easier to source duty .223 as opposed to duty 5.56 ammo.

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              • #9
                Agencies that allow personally-owned duty rifles may have some .223 chambers in the mix. It is simpler to just purchase .223 ammunition than risk someone firinga5.56 through a .223 weapon. Assuming no one would do that, it also simplifies logistics to just purchase.223 ammo.
                John from Maryland

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                • scotty_appleton814
                  scotty_appleton814 commented
                  Editing a comment
                  My agency allows personal purchases for rifles. But only in 5.56. Even going so far as to "highly recommending" some over others because not all 5.56 barrels, are really 5.56. They are just riding the line of .223.

              • #10
                Probably because. 223 is capable of being put through a .223 and a 5.56 platform without the miniscule possibility of a malfunction due to the differences in neck sizing and back pressure iirc.

                That and .223 is mostly unknown to the anti gun world. The minute you say 5.56 the masses get on some teary diatribe about us being too militarized.

                .300 would be a great police platform. Hits hard. Meant to run through a short barrel. Won't over penetrate. Leaves a big hole. Will deal with cover much more reliably vs .223.

                A 300 is basically an ak round stuffed into a 5.56 case. Its obviously a bit more complex than that but basically its a roughly 30 cal round in a necked down 5.56 brass case. All you have to do is change the barrel, re zero your sights and use (if you want) special magazines for 300 and voila you've converted your ar to 300.

                .223 5.56 is a velocity dependent round. Velocity and stability diminish significantly when the barrel drops below a certain length and twist depending on the grain size. Factor in things like the gas system length and it can get unreliable very quickly.

                Iirc roughly 10 inch is the shortest you can stabilize a 55 grain round. Green tip will tumble below 12 inches iirc.

                ​​fwiw i have a 12.5 barrel and carbine length gas tube on my AR and I've never had any reliability issues. I use the Hornady sbr ammo.

                For 223 vs 300 think of the philosophies behind 9mm vs .45.

                Small and fast vs big and slow.
                Last edited by Saluki89; 02-16-2021, 05:48 PM.

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                • scotty_appleton814
                  scotty_appleton814 commented
                  Editing a comment
                  I'm just a regular ol beat cop. Not swat or anything like. It doesn't interest me. So I just carry a regular 16 inch barrel. Works fine for me.
                  But your story reminds of a rifle class I attended that was mostly other agency swat members. 2 from the same agency were running like 9 or 10 inch suppressed 5.56 barrels but shot .223 for training. And they had about 50 malfunctions over the 3 day course.

                • Saluki89
                  Saluki89 commented
                  Editing a comment
                  Dudes are running pistol length gas systems on 8 inch platforms wondering why their 2000 dollar paperweight doesn't work when in reality that 556 ammo was meant to be shot through a 20 inch barrel.
                  Last edited by Saluki89; 02-16-2021, 05:21 PM.

              • #11
                At the risk of offending someone, it seems the duty-grade rifles now are chambered for 5.56. When we started a rifle program at my former agency, the "experts" weren't all that expert on the topic. I believe we referred to everything as .223. To this day, I'm not sure if the then-rifle instructors know the difference.

                Interesting the two SWAT dudes having reliability issues with the rifles. I've never heard of any reliability issues using .223 ammunition through a 5.56 rifle. In fact, I think my former department was still using .223 ammunition when I left. I've heard the agency went to issue FN-15's so they may have started purchasing 5.56 as personal rifles re no more. That said, while I'm a believer in short barrels and suppressors, that combination of weapon and ammunition seems more prone to go off the rails than a patrol troop with a sixteen inch barrel.
                John from Maryland

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                • scotty_appleton814
                  scotty_appleton814 commented
                  Editing a comment
                  I agree that it is a time and place for short barrels and suppressors. But for me, it's never an issue.

                  I don't really think that the .223/5.56 aspect was an issue more than it was a hardware problem if that makes sense.

              • #12
                Great video regarding barrel length
                 

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                • #13
                  No one is talking about accuracy.

                  Barrel length is usually directly proportional to the twist.

                  As the barrels get shorter reliability becomes more of a balancing act due to dwell time and twist.

                  10.5 is about the lowest you can go unsuppressed reliably.

                  Anything less than that is a literal meme.

                  Comment


                  • #14
                    I have been building and shooting ARs for about 30 years. My personally-owned department-authorized M4 has a very nice custom-made match-grade 14.5" stainless steel barrel with a 1x9 twist and a very nice adjustable single-stage match trigger. Off a bench, it will print well under an inch at 100 yards with 69 grain Sierra MatchKings, just about an inch with Winchester 64 grain Power Points (white box or black box), and a lot of times it can print around an inch or so with 62 grain M855 and 55 grain M193. It is substantially more accurate than anything I have ever shot with the 1x7 twist that is more common today.

                    Even the Mk262 77 grain OTM is more accurate with a 1x8 twist than the 1x7 twist.

                    The only reason the military uses 1x7, is because the projectile from the M856 tracer round needs it to stabilize, and the military tries to standardize stuff, so if it's got a 5.56 chamber, they want it to be able to shoot all 5.56 ammo in inventory, even if it's not intended to be used with tracers.

                    When civilians blindly buy 1x7 twist barrels because they think "it must be better because that's what the military uses", and then they shoot M193 55 grain ammo, which the military hasn't issued for combat use since going to the 1x7 twist, that mismatch is responsible for the generally poor accuracy. If you're gonna shoot 50-69 grain ammo, just get 1x9. If you're gonna shoot 55-77 grain ammo, just get 1x8. No civilian AR benefits from 1x7, because we're not shooting M856 tracers out of our civilian ARs, and any ammo heavier than 77 grains generally needs to be single-fed off a sled, because it's too long to feed out of a magazine.
                    Last edited by Aidokea; 02-17-2021, 08:35 AM.

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                    • #15
                      Look I respect you but I think we're arguing over semantics and differing definitions of reliability.

                      I don't doubt that you're vastly more knowledgeable than I but I worked at a FFL for several years and have helped the gunsmith build several ARs for customers and friends including my own.

                      We would get guys wanting the smallest barrel they can find to leave under the seat in their truck and more often than not they come back asking why their **** won't cycle or why they can't hit what they're shooting at.

                      I have a 12.5 1:7 that has been nothing but wonderful but a little over gassed. Would like to put an A5 buffer system on but cannot source one.
                      Last edited by Saluki89; 02-17-2021, 11:15 AM.

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