.300 Blackout vs 5.56

Discussion in 'AR15/10 Rifles' started by Elkeater, Aug 26, 2018.

  1. Elkeater

    Elkeater Well-Known Member

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    So I finally bought a stripped AR lower and decided to build an AR. I’ve never owned an AR of any kind but always wanted one. Anyways what I’m curious about is what caliber to go with. For simplicity sake I’m looking at either 5.56 or .300 blackout since they both use the same parts except the barrel. Right? So what’s the pluses and minuses of these two cartridges?

    Any input is appreciated. Thanks all
     
  2. imyourhuckleberry

    imyourhuckleberry Well-Known Member

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    Depends on what you expect from the cartridges whether it is going to be used or hunting and plinking, and than what kind of hunting. The 5.56 is a lot cheaper to shoot if you do not reload and is also a lot cheaper to reload if you do. If it is only going to be used for hunting such as hogs and deer I would prefer the .300 blackout, but a good heavy bullet in 5.56 like a 75 grain hornady or 77 smk is good enough for deer with proper shot placement. Do not know your level of expertise but if you are a novice I would start with 5.56.
     
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  3. Elkeater

    Elkeater Well-Known Member

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    So I do handload to answer that question. I’d like to use the rifle mostly for range time but it might get used on a deer or hog or antelope from time to time.
     
  4. phorwath

    phorwath Well-Known Member

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    Then 5.56
     
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  5. cohunt

    cohunt Well-Known Member

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    Check the regs of the states you might hunt in--- no 223 for big game in some states
     
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  6. Elkeater

    Elkeater Well-Known Member

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    I live in CO where 5.56 is not legal for big game but I hunt in MI and TX regularly where 5.56 is legal. I think I may have gotten my answer at this point. A 5.56 would be cheap and easy for the kids to shoot.
     
  7. MudRunner2005

    MudRunner2005 Well-Known Member

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    Yes, you're correct, the only thing different is the barrel... Same bolt, same mags, same everything else.

    Pros and cons...

    Pro's: 5.56 is easy to find, cheap, fast, low recoil and is a great varmint rifle and plinking round.

    Con's: 5.56 is not very powerful and because of this, it is not really good for hunting anything much larger than a coyote. It will kill, but not as efficiently as something larger with a bigger bullet. Even with a suppressor, the supersonic velocities of the 5.56 will still make it much louder than the .300 BLK.

    Pro's: .300 BLK has a larger and heavier bullet. It's purposely designed for shooting sub-sonic rounds suppressed and to be VERY quiet. Ammo is getting much more common these days and there's lots of good factory options for both subsonic and supersonic ammo. Also, if you reload, it just uses any standard .308 caliber bullet, and you can make your own .300 BLK brass from cut-down and re-formed 5.56 cases (which is what I do).

    Con's: While ammo prices and options have improved, .300 BLK ammo is still ridiculously expensive for what it is, compared to the 5.56. So, unless you have a progressive press and are loading your own, it can be very expensive to shoot. Luckily, I work for an ammo plant and one of our calibers that we make is .300 BLK, so I get 220gr subs very cheap, so I buy a bag about once a month to stock up, since I don't have a progressive press yet.

    Overall, to start out in the AR game, I too, recommend the 5.56. Make sure you get a barrel that's actually chambered for 5.56 NATO and not .223 Rem. And make sure you get a 1:7 twist, this way, if you plan on hunting hogs and deer, you can stabilize the heavier 75-80 grain bullets.
     
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  8. Elkeater

    Elkeater Well-Known Member

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    Ok. 5.56 sounds like probably the best option. So a 1:7 twist but what length? It looks like 16,18,and 20” are all options. Is there much benefit to increased length? I’m thinking 18 or 20 for shooting out to 600 yards but what’s your thoughts?
     
  9. MudRunner2005

    MudRunner2005 Well-Known Member

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    IMO, a 16" barrel is more than enough barrel for the 5.56. Standard milspec M4's run a 14.5" barrel and are rated for 660 meters effective range.
     
  10. phorwath

    phorwath Well-Known Member

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    How about for 75-80gr bullets? I never shot them, so I don't know...
     
  11. dolomite_supafly

    dolomite_supafly Member

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    8 twist will stabilize anything that is magazine fed. 8 twist will also let you shoot lightweight varmint bullets.

    7 twist will cause some lightweight varmint bullets to come apart from centrifugal force. I have had 53g SMKs come apart in a 7 twist.

    I have had an AR15 with everything from a 10.5" barrel to a custom 26" barrel. My personal preference is an 18" barrel that is not a bull barrel. Bull barrels add unneeded weight unless you are hunting prairie dogs where the barrel can heat up. But for most people a standard profile is perfectly fine without adding weight.

    As far as 5.56 versus 223 there has been several studies done showing a far amount of 5.56 marked guns actually having 223 chambers. Shooting 5.56 in a 223 will not blow your gun up. It might show some pressure on the brass but even that isn't anything to worry about. I have an AD with a 223 match chamber and it has only had 5.56 fired out of it without an issues at all. If shooting 5.56 in 223 chambers caused the gun to blow up we would hear about it a lot more.

    And while you are building it install an adjustable has block. Most ARs are over gassed so the manufacturers do not have to do warranty work on a gun that won't fire cheap, underpowered ammunition. With an adjustable has block you can tune the gun and reduce recoil, reduce has in the face, reduce crud in the receiver and make the gun more reliable. With an adjustable has block that is tuned and a quality muzzle brake an AR will Feel like a 22.
     
  12. cohunt

    cohunt Well-Known Member

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    I like the 62 gr gold dot/fusion bullets for 223 hunting, they are bonded and retain more weight than most other bullets
     
  13. MudRunner2005

    MudRunner2005 Well-Known Member

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    What about them are you wanting to know? Effective range, or barrel length recommendation?
     
  14. phorwath

    phorwath Well-Known Member

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    Barrel length... Sorry