5.56x45mm NATO, or .223 Remington?

Discussion in 'Springfield Armory AR-15 - The Saint' started by Cannot, Jan 28, 2018.

  1. Cannot

    Cannot New Member

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    My wife ordered the Saint for my birthday present today. It will be my first AR and hope will get it next week.

    According to SA's website, the caliber is 5.56 x 45mm / .223 Remington. I thought they are not exactly the same so wondered if I could use either 5.56 or .223 ammos?

    Sorry for the dumb question but I'm really confused. o_O
     
  2. CPTKILLER

    CPTKILLER Senior Member

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    "Pressure is the primary difference separating the .223 Remington and 5.56x45mm. The .223s are loaded to lower pressures and velocities compared to 5.56mm. Due to its lower pressure, you can safely fire .223 Rem. ammunition in a 5.56mm chambered gun; however, the same cannot be said in reverse."

    "However, it’s important to note that as military development of the 5.56mm cartridge has required higher velocities (via higher pressures), civilian development of .223 has essentially remained frozen since December 1962, when Remington submitted the cartridge for standardization by SAAMI. You’ll note that I didn’t say 5.56 was standardized by SAAMI, and that’s because it hasn’t been. Only the dimensions and pressures of .223 Remington have been standardized.

    [​IMG]
    Can you tell which of these rounds are .223 and which are 5.56? Because .223 Rem and 5.56 NATO share the same external dimensions, it can be hard to tell the difference.
    Because SAAMI specifies that pressures must be measured one way and the military specifies that they must be measured a different way, a direct comparison of pressure results from one lot of 5.56 ammo (measured the US Military way) with another lot of .223 ammo (measure the SAAMI way) is not possible. It’s required to test both with the same methods, instrumentation, and chamber to see any real differences.

    Theoretically, any manufacturer could make ammunition which exceeded the maximum pressure specified by SAAMI for the .223 cartridge and call it 5.56. That pressure could be exceeded by 1% or 10% – it really wouldn’t matter. It’s the functional equivalent of “+P+” ammunition – there are no official guidelines for it which ammunition manufacturers have agreed to follow, as is the case with SAAMI. You could almost consider it to be the world’s most popular wildcat cartridge, as far as SAAMI standards are concerned.

    Despite this lack of SAAMI standardization, most of the 5.56 ammunition on the market is manufactured by companies that produce 5.56 for various militaries; the 5.56 they sell to civilians is essentially identical, and thus follows the requirements and maximum pressures set forth by those military clients. As you can see from this short excerpt from a 27-page specification for US Military ammunition, military requirements are very exacting."

    https://www.luckygunner.com/labs/5-56-vs-223/
     
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  3. Devious6

    Devious6 Active Member

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    Welcome! I have an Edge on order - hoping to see it soon, too. Post some pictures of your rifle when you get it!
     
  4. Cannot

    Cannot New Member

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    Very informative. Much appreciated.

    Assuming the Saint is chambered in 5.56, just like most of AR-15s?
     
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  5. Devious6

    Devious6 Active Member

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    Cannot likes this.
  6. msymms

    msymms New Member

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    The Saint is chambered for 5.56 so you may use both .223 or 5.56 with no worries mate. It’s a hungry rifle, so feed it and enjoy. The Saint is also assembled with a M-16 bolt. 5.56 all day brother. You can also fire green tip (armor piercing) without damaging anything. This weapon could easily sell for $1,400.00. It’s a lot of bang for the buck. Literally!
     
    Last edited: Feb 3, 2018
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  7. Devious6

    Devious6 Active Member

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    I'm waiting for my Edge to come in.......aaaarrrrgggghhhhhhhhhhhh!
     
  8. Cannot

    Cannot New Member

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    Picked up the Saint last Thursday and ordered Vortex StrikeFire II Red/Green Dot Sunday. Hope I have a chance to test it soon.

    [​IMG]
     
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  9. tibbarguy

    tibbarguy New Member

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    You are setting your Saint EXACTLY how I had mine first set up. Get ready to have a blast.
     
    Cannot likes this.
  10. Kukailimoku

    Kukailimoku New Member

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    Green tip is NOT armor piercing.

    Green tips came out in the 80s when the army switch from M16A1 to M16A2 (and added the M249 SAW to the inventory). I have first-hand experience with this: Infantry OSUT at Ft Benning I had old M16 (no brass deflector, etc) and non-green tips. Got to the 82nd AB and we had the M16A-whatevers(A1? A2?) and I had my first intro to the green tip.
    The newer guns had different twist and therefore could handle a more powerful/heavier load.
    Non-green tips are M193(?) and green tips are M588(?).
    The difference is that the newer guns could consume both but the older guns couldn't consume the newer charge.
    The Army painted all the newer bullets green because they deal in massive quantities, around the world, in a stressed logistical system, with people loading mags in the dark and under duress. They needed to make sure EVERY idiot that joins the service could readily tell the difference between older and newer bullets, every time, everywhere.

    If anything, the discussion about green tips should be: why are they even still painted green? Who in the heck even still HAS and old M16 anymore? Probably less people than have genuine Lee Enfields, yet we're still having green paint in our bores because theose few people still need to tell M16 apart from M4???? All the 5.56 coming out of factories should be unpainted nowadays. There aint any more old fashion M16 bullets being made. ...or are there????
     
    Last edited: Nov 28, 2019