Quantcast

Using M855 Green Tip in 1/7 Twist Colt AR

Discussion in 'Rifle Country' started by Bedfordtec, Oct 20, 2019.

  1. Bedfordtec

    Bedfordtec Member

    Joined:
    May 28, 2019
    Messages:
    35
    I have a Pre Ban Colt AR-15 carbine with lightweight barrel. 1/7 Twist. Usually I only fire M193 55 Grain Ammo in it. Are there any drawbacks to using M855 Green Tip 62 grain in it such as reduced barrel life. I fired a few rounds and I believe it shot a couple of inches low at 100 yards.Thanks, Bedfordtec
     
  2. jmr40

    jmr40 Member

    Joined:
    May 26, 2007
    Messages:
    12,546
    Location:
    Georgia
    No drawbacks. In fact it may well shoot better.
     
  3. briansmithwins

    briansmithwins Member

    Joined:
    Aug 1, 2005
    Messages:
    4,202
    It should shoot better as that twist rate works better with longer bullets like the M855. Barrel life should be better with the heavier slower bullets as well. I wouldn’t expect a huge difference in barrel life as 556 tends to burn the throat of a barrel out much faster than a larger bore rifle.

    BSW
     
    Mosin Bubba and Charlie98 like this.
  4. FL-NC

    FL-NC Member

    Joined:
    Feb 10, 2016
    Messages:
    4,944
    Location:
    Fl panhandle
    That SS109 is exactly what that rifle is meant to fire. Same twist rate and round as what was standard issue since the late 80's, although it is being phased out now. That said, be advised that SS109/M855 is very inconsistent.
     
    Walkalong and TikkaShooter like this.
  5. MTMilitiaman

    MTMilitiaman Member

    Joined:
    Apr 28, 2005
    Messages:
    3,146
    Location:
    Missoula, Montana
    The military went to 1:7 twist specifically for the M855 "Green Tip" and its associated M856 tracer round. The M855 has a steel penetration over a lead core. The complexity of the design makes it marginally less accurate and consistent in performance than the more basic M193, but it is still plenty effective within its range, and better at penetrating some things. On that note, some ranges don't like it, because they feel it can damage their plates. I shoot a lot of M855 though with no complaints. It is accurate and effective enough for my uses. For everything else, I run 62 GR Barnes TSX.

    The regular M855 shouldn't have increased wear on your rifle, but the newer M855A1 is loaded hotter and has a reputation for chewing up feed ramps.
     
  6. Nature Boy

    Nature Boy Member

    Joined:
    Apr 21, 2015
    Messages:
    4,351
    My AR shoots the M855 better than the M193
     
  7. MTMilitiaman

    MTMilitiaman Member

    Joined:
    Apr 28, 2005
    Messages:
    3,146
    Location:
    Missoula, Montana
    Accuracy difference isn't huge in my Colt 6960, but I do notice that M855 tends to be a bit less consistent in its accuracy. Some of it seems to shoot about the same as M193, some of it shoots maybe a MOA more. Either way, it can be hard to tell the difference in a lot of the shooting I do, with the red dot, and the rate of fire I try to maintain with the AR. I buy the M855 as much for the ammo cans and the fact it comes on stripper clips, and the fact I like rounds like the 62 gr TSX, the Federal FBIT3, Speer 64 gr Gold Dot, and Federal Fusion MSR for defense.
     
  8. Charlie98

    Charlie98 Member

    Joined:
    Nov 20, 2017
    Messages:
    1,725
    Location:
    McKinney, TX
    Same here, although once in a while Federal will package M193 in that 420rd can on strippers, too. It's not the best bargain, but I get it when I need to reload my stash of strippers and sleeves.

    I've found M855 to be about as accurate as M193 in my AR carbines, no more, no less. The only caveat to that is my Colt H-Bar, which detests anything 55grn, and lets you know it in pretty short order. Briansmith is correct... the chamber and throat will degrade, most likely, before the rifling does... particularly if you are doing rapid fire strings.
     
    trevally likes this.
  9. C-grunt

    C-grunt Member

    Joined:
    Jun 12, 2005
    Messages:
    3,940
    Location:
    Phoenix Az
    Ive never found M855 to be as accurate as M193 in my rifles. Not saying it's bad or anything but M193 always had a slight edge on accuracy. Top off that M193 tends to be a bit cheaper, I never buy M855 anymore.

    But dont take that as me telling you not to buy M855. It's a good round.
     
    TikkaShooter, BSA1 and Mosin Bubba like this.
  10. Mosin Bubba

    Mosin Bubba Member

    Joined:
    Jul 5, 2012
    Messages:
    1,237
    I never got the appeal of M855 to be honest. It's more expensive than FMJ, it's usually a little less accurate than FMJ, and the penetrator doesn't do anything for civilians (and even the military doesn't like it any more).

    In the grand scheme of things M193 vs M855 isn't a big deal, but I don't buy the green tips.

    As others have said, it's absolutely fine for your 6920, in fact the Colt M4s were designed to shoot it.
     
    js8588 likes this.
  11. BSA1

    BSA1 Member

    Joined:
    Apr 20, 2011
    Messages:
    7,169
    Location:
    West of the Big Muddy, East of the Rockies and Nor
    According to the Internet and even comments on this thread M855 should be more accurate than M193 in a 16” 1 in 7” barrel but the opposite is the case with this particular gun.

    This gun is very accurate with PMC .223 55 gr. FMJ. No I didn’t type that wrong. It loves PMC .223 even though it has a 5.56 chamber.

    I have found Federal M855 to be inconsistent in both my 5.56 and .223 Wylde AR’s. It acts like it wants to give me a good group then it starts throwing flyers. I plan on getting some 62 gr. FMJ (without the steel core) to see how it performs in both guns.

    It just goes to show that every gun is a separate rule onto itself.
     
  12. Charlie98

    Charlie98 Member

    Joined:
    Nov 20, 2017
    Messages:
    1,725
    Location:
    McKinney, TX
    I recently bought some 62grn BTHP component bullets to try out... if the 1:7 rifling is supposed to be better with longer/heavier bullets, I might as well see if I can get better accuracy if I'm going to go through all the trouble to prep brass and handload.
     
  13. Walkalong

    Walkalong Moderator Staff Member

    Joined:
    Nov 20, 2006
    Messages:
    59,455
    Location:
    Alabama
    As long as the bullet is stabilized, the quality of the bullet is much more important to accuracy than spin rate.

    Shoot it, it won't hurt your rifle.
     
  14. TikkaShooter

    TikkaShooter Member

    Joined:
    Aug 9, 2016
    Messages:
    358
    Location:
    NE Georgia
    I have a few ARs, two prefer M193 to 855 and one that is more accurate with 855. My father and I had a bolt action 30-06; as he passed away, I have both and each still prefers a different load. Neither is a picky eater; that being said each is more accurate with the load they prefer.

    IMO, ARs or whatever are no different.
     
  15. herrwalther

    herrwalther Member

    Joined:
    May 1, 2013
    Messages:
    4,920
    I shoot M193 and M855 through my PSA build AR regularly. Accuracy wise, very little difference. I can find more difference in my shooting if I had caffeine that morning or not compared to 855 vs 193. As far as your rifle is concerned, it was designed with M855 in mind.
     
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice