GECO 5.56 White Box Ammo

Discussion in 'Ammunition & Reloading' started by JamesBigBlueUK, Sep 20, 2020.

  1. JamesBigBlueUK

    JamesBigBlueUK New Member

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    Just opened up my first box of this Geco white box 5.56 NATO ammo. I noticed while loading my mags that the rounds looked more like .223 than 5.56. I grabbed another box of 5.56 American Eagle to compare them. These Geco rounds are shorter just like .223 rounds. I then grabbed a box of Frontier .223 and they are the exact same length as these Geco rounds. Anyone else came across this? The Geco rounds are stamped 5.56 NATO, but these are the only 5.56 rounds I've ever bought that were the same length as a .223 round. It's not a big deal to me. I'm just curious if this is normal for these Geco 5.56 rounds.
     
  2. Ghost1958

    Ghost1958 Well-Known Member

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    I've bought some Geko 5.56 before but to be honest I never checked em that close.
    They functioned fine. POI was acceptable. Seemed to feel a bit hotter than 223, but I couldn't swear to that either.
    In general i general I'm now wondering why I'm posting to this as I am obviously of no help at all.

    I'll go sit in the corner now
     

  3. Mercator

    Mercator Well-Known Member

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    You mean longer cases or bullets?
     
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  4. Oldoutlaw

    Oldoutlaw Well-Known Member Supporter

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    Also, what are your bullet weights in each you mention. Larger bullets may be longer than smaller bullets.
    Besides, I think the only difference between 5.56 and 223 is the loading.
    5.56 having much higher pressures than 223.
     
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  5. JamesBigBlueUK

    JamesBigBlueUK New Member

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    The difference in length is the bullets. The cases are identical, or very close to identical. I just compared American Eagle 5.56 55 grain FMJ XM193, American Eagle 5.56 62 grain FMJ-BT XM855FL, Frontier .223 55 grain FMJ (Hornady Bullets) FR100, and these Geco rounds. Both American Eagle 5.56 rounds are the same length even though one is 55 grain and the other is 62 grain green tip. They have longer bullets. These Geco 5.56 rounds are 55 grain FMJ-BT and are the same length as the Frontier .223 55 grain FMJ rounds. This is the first time I've ever seen a 5.56 round have the same size bullet as a .223 round. It's always been easy for me to tell what I'm loading into a PMAG based on the tip of the round......until tonight. The tip of the bullet in these Geco rounds in relation to the PMAG is what caught my eye and made me realize something wasn't quite right.

    Just took a break and opened more boxes from other brands. I checked PMC 5.56 55 Grain FMJ-BT and PMC 5.56 62 Grain LAP green tip. Also checked Olympic 5.56 62 Grain green tip and PPU 5.56 55 Grain FMJ-BT M193. They are all the same length. This Geco ammo is the only ammo I have that is "short" like .223. Weird.
     
    Last edited: Sep 21, 2020
  6. G66enigma

    G66enigma Well-Known Member Supporter

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    Might it be just a given box or lot# involved?


    OAL: I'd be really surprised if a manufacturer were to allow a change in the length at the shoulder, with the ramifications involved. (Not that overall length, base-to-tip, would matter.)

    As others have pointed out, the only material difference should be the case capacity of powder (~1.05% more in 5.56 than .223).

    If it's only Geco, and if you've only got one box (or one Lot#) of it, I wonder if they simply spec'd a particular set of parameters on this one run of cartridges that was different than a "normal" run. It'd be interesting to see if the base-to-shoulder or base-to-tip length varies at all across lots.


    Only reference point I have is from 10+ years ago, with a Stag 5.56 I had at the time. Don't recall ever noting clearly-visible differences in length of cartridges, across 15+ different types used in the gun (5.56 and .223 ... Hornady, Federal, Am.Eagle, Prvi Partizan, others). Never used calipers on them, to be fair, but simple inspection of different makers' cartridges showed no visible difference to me.
     
  7. Mercator

    Mercator Well-Known Member

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    It is normal. GECO probably uses the same 55 gr bullet in their 5.56 as in their 223.
    I have HSM 223 90 gr. It would not fit in the magazine in my Ruger American, even though the caliber is correct.
     
  8. JamesBigBlueUK

    JamesBigBlueUK New Member

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    Hmm. This surprises me a bit. To me, there's always been a clear difference between 5.56 and .223 when I load my magazines. The tips of the 5.56 rounds are closer to the edge of the magazine than .223 rounds are. Anyway, I opened up three more boxes of Geco 5.56 and they're all the same. I'll post a pic when I get a chance.
     
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  9. JamesBigBlueUK

    JamesBigBlueUK New Member

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    Thanks. This is definitely the first time I've come across this issue.
     
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  10. Oldoutlaw

    Oldoutlaw Well-Known Member Supporter

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    I have seen some differences before over the decades. Need to remember this. The European countries in particular seem to only produce 5.56 to NATO specs. Not for 223. It also must fit all NATO countries magazines and weapons. So, same ammo. But, some countries use different base weapons. Still 5.56 caliber, but may have different feed systems and magazine sizes. One size has to fit all type of situation.
    Some do produce 223 for hunting/target also. Like Geco does. RUAG owns Geco and other brands imported for sale here.
    Yours should be very good ammo and shoot well.
     
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  11. JamesBigBlueUK

    JamesBigBlueUK New Member

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    From left to right: American Eagle 5.56 55 Grain, American Eagle 5.56 62 Grain, Frontier .223 55 Grain, Geco 5.56 55 Grain
    ammo 001.jpg
     
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  12. Sniper03

    Sniper03 Supporting Member Supporter

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    James
    It is my opinion that Geco and some others load their bullets to 223 Remington Length Specifications regarding the depth of the Bullet in the case. There is a reason they do that. It eliminates any problem with the Bullets being seated to 5.56 NATO Depth. (Length) If the True NATO Length Bullet depth were to be fired in a "True" Remington 223 Chamber the pressure would spike and possibly cause damage to the rifle and the shooter. Most ALL AR-15 Companies are doing their rifles in 5.56 NATO Chambers for a reason.
    The reason the Throat in the 5.56 NATO Chamber is Longer (Deeper in the Barrel than the Length of that in the true 223 Remington Chamber.
    The 5.56 NATO Rounds are normally loaded hotter to military standards for the Military than the 223 Rounds. So with the true 223 Remington Chamber the chamber NOT HAVING what is called Fee Bore or Lead the Bullet would already be tight in the chamber causing the pressure in the 223 Remington Chamber to SPIKE! if a 5.56 NATO Round is fired in it.
    You are able to shoot 223 in the 5.56 NATO Chamber and the Wylde Chamber. And you can shoot 5.56 NATO in the Wylde Chamber just fine with no problem.
    Here is an Xray of the two Chambers to compare the Free Board or Lead in the Chamber.
    You can see the difference where the Riflings Start on each. The Yellow Line represents
    the Case Mouth location fo each.
    Cut away of 223 vs 5.56 Chamber.jpg
    You can see the Free Bore on the 5.56 Xray on the Right compared to where the Riflings start to the True 223 Chamber on the Left. That is the difference.

    03
     
  13. JamesBigBlueUK

    JamesBigBlueUK New Member

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    Thanks for that pic.
     
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