7.62x51 nato vs.308 win does it matter?

Discussion in 'Rifle & Shotgun Discussion' started by doubletap007, Oct 22, 2011.

  1. doubletap007

    doubletap007 Active Member

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    my armalite ar10 seems to shoot 7.62nato rounds a little more accurate than 308win rounds.even high quality 168gr.bthp rounds such as nosler and hornady sst are really no more accurate than a plain old remington coreloct 150gr.
    i did find the fusion 165gr to be a very accurate bullet but still not as accurate as a cheap 7.62x51 nato round.
    is there a reason the nato round is more accurate even though armalite says either is just fine?some expert advise would be helpful...thanks in advance
  2. Skang

    Skang Well-Known Member

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    It's just your barrel like that ammo better.

    And 7.62 is not same as 308. casing and head spec are different.
  3. HollisOR

    HollisOR Active Member

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    Pick up a reloading manual. 7.62 NATO is a specific round based on the needs of the military, it is based on the .308 Winchester. Military cases have always been thicker than civilian's. Also the military crimp the primers into place. Go to Brownells and look at head space gauges, reamers and case gauges.(they are the same) The .308 Win also has hotter loads available to it than the military load.
  4. doubletap007

    doubletap007 Active Member

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    so in reallity the 308 round should shoot straighter since it is a much hotter round?
    i did notice looking at upgrading to the triple lapped match grade barrel that it will stabilize up to a 200gr bullet
    so could that mean that my stock barrel is maybe intended for a lighter round than the 168gr i have been shooting?
    the armalite website says my rifle is 1.5to2moa but the sst match barrel is 1moa for the low price of only $500
  5. HollisOR

    HollisOR Active Member

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    No .308 is not necessary hotter, it can be. A good book, the Accurate rifle will discuss accuracy issues. .308 can be loaded hotter. It also can be loaded not as hot. The rifling and the bullet needs to match (find the right bullet for the barrel) that find the right load (speed) for the bullet. Military .308, if memory is right is 147 grain @2700fps. You can find the military loads on the net and maybe in some reloading books. The benefits of reloading, you can build a round specifically for your rifle.
  6. doubletap007

    doubletap007 Active Member

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    thank you hollisor,sounds like a book i need to read.what you said about finding a load that matches the barrel sounds logical too.
    guess i over looked the fact that not every barrel is created equal.
  7. HollisOR

    HollisOR Active Member

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    Three of us bought Win Mod 70 in .338 Win Mag. We bedded them and set them up the same. One would not group. Barely group with a 215 gr bullet. We rebedded it and started all over, still the same result. Finally we cut off about 1/2 inch of the barrel and re-crowned it. It was sub 1 MOA after that. The other story, I had regular reloads when I but a new scope on my Ruger in .308. It was clover leafing at 100 yards. So I go shooting with a friend and naturally bragged about it. Unfortunately I brought some European NATO to shoot, at 50 yards it was all over the place over 6 inch groups. Sometimes find a good load is easy. Another great book is Ken Water's Pet Loads. It has really good starting loads.
  8. civilian75

    civilian75 Well-Known Member

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    How much more accurate? What is your upper's barrel length and twist ratio? Chamber actual dimensions, lead, etc.? Gas port opening? There are sooooo many more variables affecting accuracy. I have found in my bolt that bullets in and around 168gr can be a bit finicky about the most accurate charge; hottest may not be most accurate. In 150-155 and 175-180gr, hottest is most accurate. But that may not hold true for a different barrel length rifle or semi auto rifle (with gas port), or just a different powder.

    You can consider yourself lucky you get best accuracy with the cheaper stuff. That is, unless you expected more. I do not own a semi-auto in 308/7.62 but I'd venture to say that is you are getting ~1.0 MOA at 100yd, that's about right.
  9. doubletap007

    doubletap007 Active Member

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    right you are sir!....just so happens last night i decided to check to see if my aftermarket quadrail was too tight or pinching the gas tube
    and noticed the small vent hole was a little plugged as you mentioned,i just took it out and got it on the money at 100yrds so its sub moa now at 100yrds with my new leupold scope and cheap old fusion 165gr,i was lucky to meet some other nwfa members out there who shot it too and they were very accurate with it too but after they left i got the new scope dialed in and its a tack driver now.
  10. doubletap007

    doubletap007 Active Member

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    also,it is 20inch barrel 1:11 twist.not sure of other specs you asked about.i did find i was not utilizing the 2 stage trigger right and wow what a difference it makes when you use it right!go figure.