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7.62x51 load data question

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  • unicom

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    Just want to double check. But when using data for 308 win, should I be reducing it by roughly 10%?


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    unicom

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    AR10 should handle most .308 loads just fine. But build your loads by carefully working up to them and be cautious of mil brass as the heavier 7.62x51 case walls render a slightly reduced volume for powder.

    I did about a 10% reduction in powder for the 7.62x51 load. So instead of the 44.7gr for 308 I went with 40.2gr load


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    unicom

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    Thanks again for the help from all you guys/gals that answered.


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    TexMex247

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    Sounds like you reduced a bit more than necessary. When I tested NATO lake City vs 2 commercial brands of 308 the internal case capacity was only about 1% difference. It's a common myth but nothing wrong with being cautious. I have some nice loads dialed in for a bolt rifle that are approaching too much with my AR10. At 43.5gr of IMR 4064(w/175gr pills) I'm getting noticeable case head swipes from the extractor and bolt.

    It's not a brass destroying load but it definitely leaves a mark. I've decided to shift to 150s. The rifle has showed some potential in the past with them. I still like the thought of a one load two gun solution but realistically I doubt I'll ever stretch the AR10 beyond 300 yards. It seems it's at 600+ yards where the heavies really shine.

    After a few batches I bet you wind up within 2 grains of max and not 4. Once again, no issues with be cautious, you just might waste a pound or so of powder along the way.
     

    unicom

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    Sounds like you reduced a bit more than necessary. When I tested NATO lake City vs 2 commercial brands of 308 the internal case capacity was only about 1% difference. It's a common myth but nothing wrong with being cautious. I have some nice loads dialed in for a bolt rifle that are approaching too much with my AR10. At 43.5gr of IMR 4064(w/175gr pills) I'm getting noticeable case head swipes from the extractor and bolt.

    It's not a brass destroying load but it definitely leaves a mark. I've decided to shift to 150s. The rifle has showed some potential in the past with them. I still like the thought of a one load two gun solution but realistically I doubt I'll ever stretch the AR10 beyond 300 yards. It seems it's at 600+ yards where the heavies really shine.

    After a few batches I bet you wind up within 2 grains of max and not 4. Once again, no issues with be cautious, you just might waste a pound or so of powder along the way.

    I appreciate the info. I don’t want to unnecessarily waist powder. The load data was from Hornady using IMR4895. The 308 showed 44.7gr to be just below the max at 46 something. I most likely won’t be loading a lot of nato just happened to have some brass lying around. Thanks again for the info.


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    popper

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    casehead swipes are not an indication of hot load, just too much gas too early. I don't go much over 40gr of any 'proper' powder, extra fps isn't needed. Mixed retail & LC brass. This is 168Amax @ 100 several yrs ago, dpms carbine. It does about the same with 168gr GC cast, actually MOA @ 200.
     

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    TexMex247

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    Funny that you just posted that popper... I shot some Hornady black 168gr amax this last weekend and it shot better than anything else I've ever run through that rifle including federal GMM in 168 and 175gr. Needless to say I ordered 500 AMax bullets last night.

    I did save 5 rounds to spec out and chronograph ahead of the bullet shipment.
     

    TxStetson

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    Funny that you just posted that popper... I shot some Hornady black 168gr amax this last weekend and it shot better than anything else I've ever run through that rifle including federal GMM in 168 and 175gr. Needless to say I ordered 500 AMax bullets last night.

    I did save 5 rounds to spec out and chronograph ahead of the bullet shipment.
    Don't waste your time trying the Hornady 178 gr match projectiles in your DPMS. At 100 yards they resemble a shotgun pattern. 168 gr SMK's have worked really well in my Remington R-25 which was made by DPMS.
     

    TexMex247

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    What do you use at 1k yds I'm getting into long distance

    Hell I'm still working on 1 MOA at 100. However from most of my reading people are running heavies (175&up) with Berger otm bullets. Get ready to open up the wallet if you go that route. Those are about 70 cents a pop. As far as factory ammo, I'm not sure. They say 168s tumble or yaw at 1k but I've never shot that far...at least not on purpose. Lol
     

    avvidclif

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    Just want to double check. But when using data for 308 win, should I be reducing it by roughly 10%?


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    Since every rifle is unique, bore, rifling, etc the rule of reloading has always been start low and work up. A caveat though. There are some loads that have a minimum charge as they have been known to explode. Research is your friend.
     

    mad88minute

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    Since every rifle is unique, bore, rifling, etc the rule of reloading has always been start low and work up. A caveat though. There are some loads that have a minimum charge as they have been known to explode. Research is your friend.
    Explode or hang fire, I was just reading up on reduced loads in a 338 win mag and there were cautions about short but perceived delays from primer strike to ignition.

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    mad88minute

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    Reduced in what way? Reduced from max charge or for low recoil?
    Loading below posted minimum for reduced recoil.

    When you go too low you have to start considering case fill %. If the powder doesn't fill enough volume and the position of the firearm places the powder away from the primer, the primer won't ignite the powder efficiency.

    I was reading a thread about a guy trying to download 338 winmag to achieve 338 federal, or 308 win recoil & velocity. Hang fires began when he got too low on case fill %.

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