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Will a 1:7 barreled AR shoot a standard 5.56 55 gr bullet well?

Discussion in 'General Firearms Forum' started by WarEagle32, Jul 4, 2012.


  1. WarEagle32

    WarEagle32
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    I have a 1:9 M4 that I have shot 55 grain bullets through very well for years. I am seriously thinking of buying another AR thats a top tier M4 which has a 1:7 barrel. I have a ton of 55 grain 5.56 stored up. I know the 1:7 will shoot 62gr green tips well, but does it also do well with 55's because I don't want to have to buy more separate larger ammo anytime soon. Thanks for any info!
     

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  2. Zombie Steve

    Zombie Steve
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    Decap Pin Killa

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    Shoots 'em just fine.
     

  3. WoodenPlank

    WoodenPlank
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    Who?

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    Some people will swear up and down that they got crap accuracy from 55gr with a 1/7 barrel. I've owned several (16, 14.5 and 10.5) 1/7 barrels that were plenty accurate with 55 grain ball, especially federal in various forms. 2-4 MOA is typical, but I have seen as good as 1MOA. My 10.5 SBR will shoot better groups than I will ever get with my 4MOA Aimpoint with Federal XM193.

    As usual, YMMV etc...

    Sent from the USS Sulaco, while nuking the site from orbit.
     
  4. arclight610

    arclight610
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    My 1/7 shoots 55gr just fine. In fact, I use 55gr almost exclusively.
     
  5. Decguns

    Decguns
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    The 55gr FMJ will shoot fine in a 1-7 twist. Under 300 yds, you'll never notice that it's over-stablized. The faster rifling twist actually increases penetration on hard targets like car bodies and GI helmets just like it does for the SS109.

    The only problem I've ever had with 55gr ammo in a 1-7 is shooting soft points at velocities over 3200 fps. The projo is spinning at 300,000+ RPM, and light skinned varmint projectiles can literally self destruct after leaving the barrel. About 3 feet from the muzzle of my Colt HBAR, I'd see a little black puff ball where the projo blew apart.
     
  6. Zombie Steve

    Zombie Steve
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    Decap Pin Killa

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    Good point. I wouldn't go with varmint bullet construction or anything lighter than 50 grain bullets.
     
  7. APERS

    APERS
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    55gr works fine in my 1-7" (BCM),, out to around 200yards or so. Also own a 1-9'' Stag that I loaded alot of 52gr BTHP (Nosler) Match bullets for..which I tried the other day while zeroing BCM at 50 yards. They actually grouped tighter than the 68, 62 & 55 gr bullets! Im starting to believe that quality of bbl in an AR has alot more to do with accuracy than twist rate..?? As a side note, both rifles will group the best with 64gr Win. Power Point bullets. At 50 yards that is.. boat tail bullets with excel at longer ranges as a rule of thumb. 250yds and beyond.
     
  8. WarEagle32

    WarEagle32
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    Interesting because I use TAPs and ballistic tips a lot! However pure copper Barnes TSX's are by far my favorite!
     
  9. SCSU74

    SCSU74
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    St. Cloud Proud

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    Xm193 works great out of my 6920 1/7 out to 50 yds. It works less great I further out I go. At 100 it hits very low and right. Switching to 62g duty ammo at same distance hit dead on. Ymmv


    Sent from my iPhone... which probably auto-corrected something wrong
     
  10. AustinTx

    AustinTx
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    You have noticed something that most gun owners won't believe. Until you do the actual calculation, most people won't believe the bullet is spinning that fast. My son-in-law found that out with light bullets in a 25-06.
     
  11. Redfire SVT

    Redfire SVT
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    Depends on who you ask! But, IMHO, it will shoot them just fine.
     
  12. AustinTx

    AustinTx
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    Well, I didn't ask you, anyway.
     
  13. Redfire SVT

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    I was referring to the OP, who asked for my reply just as much as he did yours. Thanks!
     
  14. AustinTx

    AustinTx
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    Please excuse me. I don't know what I'm doing most of the time, anyway. I just come here to have fun and maybe even learn something.
     
  15. Tiro Fijo

    Tiro Fijo
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    The rate of twist formula is really for bullet LENGTH and not weight, hence your Barnes SC bullet being longer (copper less dense than lead) should do fine.
     
  16. Haldor

    Haldor
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    Works great. That is how my Colt AR15-A2 is barreled (1:7) and all I shoot through it is M193 ammo. I am getting 3" groups at 100 yards with this combination.
     
  17. eracer

    eracer
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    Where's my EBT?

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    I have an 18" 1:7 middy that shoots 1 MOA with 75gr TAP, but only 5 MOA with 55 gr. M193. My 1:9 carbine shoots both M193 and 75 gr. Hornady Match to 1 MOA.

    Point is, different barrels handle different ammo differently.