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55 gr vs 62 gr in 223?

Discussion in 'Rifle Country' started by Shrinkmd, Sep 29, 2007.


55 or 62 grain?

  1. 55 gr M193 all the way

    28 vote(s)
  2. 62 gr, they switched to ss109 for a reason

    24 vote(s)
  3. 123 grain 7.62x39 is the answer!

    8 vote(s)
Multiple votes are allowed.
  1. Shrinkmd

    Shrinkmd Well-Known Member

    Not that much is available in either these days, but for your plain jane 20" AR-15, which do you prefer? I thought that the ammo oracle seemed to say that the M193 out of a 20" barrel was superior, but I need to recheck that.

    Let the people decide...
  2. Zeke Menuar

    Zeke Menuar Well-Known Member

    I guess it depends on what you plan on using your AR for.

    I use 55gr for general purpose bumming-around-ammo and 75gr for longer range precision (for me) shooting. This is in a 20" govt profile AR.

  3. otomik

    otomik Well-Known Member

    mk262 should be in there.
    when the same gun with the same twist barrel can shoot all of these it's not a very contentious issue.
  4. glockman19

    glockman19 Well-Known Member

    I have M193, SS109, and M855. .223 & 5.56 depending o rifle. Lake City 5.56 for AR's, .223 for mini-14. All for different targets. Mostly Lake City, Remington, Winchester Q3131 and Federal American Eagle
  5. SoCalShooter

    SoCalShooter Well-Known Member

    Plane jane barrel would have 1/9 twist usually so 55gr rounds would be find. Depends on the application. I shoot 55gr at 100 yds for match but at 200 and 300yds I shoot 77gr.
  6. DMK

    DMK Well-Known Member

    Barrel length has nothing to do with it. Rate of twist is the deciding factor, just like any rifle.

    Go back and read the Oracle again: www.ammo-oracle.com

    1/12 twist is good for 55gr or lighter bullets (I think 60gr will stabilize too)

    1/9 twist will stabilize something like 40gr. up to 73gr. Some 1/9 twist barrels will shoot 75gr. OK

    1/8 twist and 1/7 twist can stabilize 77gr. You wouldn't want to shoot anything lighter than 55gr. in a 1/7 though. My 1/7s don't even seem to shoot 55gr as well as my 1/9 and 1/12 twist rifles.

    Also keep in mind that it's bullet length that's the factor not weight. A 75gr bullet happens to be longer than a 55gr because of the added mass (keeping it at .224 diameter). However, civilian 62grs are a different length than Military 62grs because they don't have the steel penetrator core inside them like the milspec rounds do.
  7. DMK

    DMK Well-Known Member

    So, to answer the question posted:

    I shoot Black Hills 75gr. in my 1/7 twist barrels (one 16" and two 20") and keep some 77gr mk262 rounds in a few mags for SHTF type stuff.

    In my 1/9 and 1/12 barreled ARs (one 20"), I mostly shoot 55gr M193, some Remington 55gr and some Black Hills 52gr. The 1/9 (one RRA 16" and a Bushmaster 20") have shot some 75gr pretty well too.

    55gr is generally the cheapest so it gets shot more (so the 1/9s and 1/12s get more use).
  8. rino451

    rino451 Well-Known Member

    Fixed it for ya. SS109 is the bullet designation (62 gr. steel core) while M855 is the cartridge designation with the SS109 bullet.

    I shoot both 55gr and SS109 reloads usually out of a 14.5" 1/9 5.56 barrel. I've shot the 55gr. out to 325 yards with 4x optics and 200 yards with irons and they group ok considering I never "worked up" the reloads. And although I haven't really shot my SS109 reloads at distance, I have shot ADCOM M855 out to 175 yards and it seems to group ok shooting off hand with irons.
  9. RockyMtnTactical

    RockyMtnTactical Well-Known Member

    M193 is better than M855 if you are just talking about the best performer vs. soft tissue.

    M855 does better against a variety of barriers because of the steel penetrator. Also, M855 has better BC and is better for longer ranges.

    Still though, shot placement is your best friend.
  10. M2 Carbine

    M2 Carbine Well-Known Member

    I handload mostly 52-55gr bullets.
    My range is only 110 yards and in everything from Kel Tec .223 pistols to a NM RRA I get the best accuracy with the lighter bullets.
  11. HorseSoldier

    HorseSoldier Well-Known Member

    SS109 is the Belgian designation of the round (designed by FN). M855 is simply the US designation for SS109, which is the NATO standard load. Also commonly known as "green tip" here in the US, or (at least in military circles) by its DODICs (A059, AA33 when on stripper clips, etc.).

    I've heard a number of people say that 1:12 will stabilize 62 grain rounds if they are all lead and not SS109 type rounds. Don't know how true this is and suspect it may vary to a degree from gun to gun in any case.

    From experience, 1:12 definitely won't work with steel cored M855/SS109. Army guidance is "wartime emergency use only," but years ago I saw a 'Guard unit trying to zero and qualify with M16A1s with M855 ammo (their ammo guy apparently made a mistake or did not understand there was an issue). Rounds were keyholing at 25 meters and guys were having trouble getting rounds on the paper at all, much less grouping, etc. I don't think they even bothered trying to go on down to the qual range at all after the fiasco zeroing.
  12. toecutter

    toecutter Well-Known Member

    They created SS109/M855 to improve the effect on area targets out to 800m in the M249. They just pushed it to the M16 platform so they wouldn't have to support different cartridges. For the SHTF ammo, it's all loaded up with sierra 53gr HP-BT match, I've used these out of a .22-250 out to 500 yards and seen absolutely DESTRUCTIVE results on coyote and groundsquirrel. For blasting ammo, I usually load 55gr. I used to load SS109/M855 but the added cost of the projectiles really didn't buy much "extra penetration". The thing to keep in mind is m855 is still considered ball, the main reason there is steel up in the nose is to change the center of mass in the projectile. When I did some tests on m855 vs xm193 on plate steel, the M855 really only got an extra 10-20% better. Figure, you're paying between 1.5-2x as much does it really pay for itself? Now, when you can find a production run of brand new isreali M855 for $4/box M855 is good enough!
  13. rangerruck

    rangerruck Well-Known Member

    well.... this one is rife with answers, all proly correct.
    If you wanna go with origional military thoughts and designs, the the 55 grains is what you want. Origional thinking was, to be able to carry lots of rounds, most fighting will be up close, and will need lots of ammo poured in to the situation. the 55 grn bullet in a 1/12 or 1/14 twist bbl is highly unstable, and not very accurate, which is fine out to 100 yds, or in a raid or ambush. the high unstable rate is good, because, when it hits tissue, and with the slower twist rate, it is supposed to immediately yaw, and gimble, thereby injuring your typical commie.. er ...vc... ahh, you know, the enemy.
    The thinking of the Generals at the time was , if it kills them, fine, if it does not, it takes two or more of their buddies to carry him away, which is very good for us.
  14. DMK

    DMK Well-Known Member

    Again, it's bullet length, not weight that is the factor.

    M855 rounds and real SS109 rounds have a steel penetrator. Steel is lighter than lead so the round is longer to weigh that much. The solid lead core commercial 62gr rounds are shorter than military steel cored penetrators. The shorter commercial 62gr rounds can probably stabilize quite well in the 1/12 twist (hadn't tried any myself).

    You could make a wood core 45gr that would require 1/7 twist to stabilize because it would be so long.

    BTW, the reason the military went with 1/7 twist was to stabilize the long tracer rounds (the tracer fuel weighs much less than lead or steel). If it wasn't for them, 1/9 twist would have stabilized M855 just fine (probably even better). Of course today that's serendipity since 75gr and 77gr HPBTs work great with 1/7 twist.
  15. DMK

    DMK Well-Known Member

    I'm not sure about 1/14 twist, but 55gr can be highly accurate in a 1/12 twist.

    It's an urban legend that 55grs were unstable in flight in Vietnam era M16s. The round flies true. It tumbles when hitting a soft medium (such as meat or ballistic gel), but all FMJs do this, even M855 and 7.62 M80. The horrific wounds the M193 caused were due to the projectile tumbling sooner than heavier bullets tend to do and because it had only a thin jacket and struck at high velocity, the rounds tended to come apart when they tumbled.

    Modern 75gr and 77gr HPBT projectiles also tend to exhibit this same terminal behavior.

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