How does 75 gr 5.56 do out of a 10.5" barrel - Page 2

How does 75 gr 5.56 do out of a 10.5" barrel

This is a discussion on How does 75 gr 5.56 do out of a 10.5" barrel within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; In the words of a TV personality. It will kill....

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Thread: How does 75 gr 5.56 do out of a 10.5" barrel

  1. #16
    Member Array creek21's Avatar
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    In the words of a TV personality. It will kill.

  2. #17
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    Quote Originally Posted by Smitty901 View Post
    When it comes to Ar's and a lot of things not right or wrong often just different ways to do things. With your weapon you plan to use it short range under 100 yards and to focused on 50. Consider going low mount on your sight. It will make you much more accurate at close range. The only reason for the high mount would be co-witness with iron sights. I would argue for you stated purpose with what you have mount I iron sights may not be a big concern. You could always have a set of flip ups ready to mount if you choose to latter. I personally have never been a big fan of AR pistols . But Army train marksmen are doing some impressive shooting with the short barrels.
    The reason the Army went to using the heavier rounds was to stabilize the bullet at longer range, The current m855A1 (improved m855) round is still a 62 gr but the bullet it's self is different . I would not recommend it for home defense.
    it was not improved because it was defective, but to penetrate steel and block walls better and it does. Any of the good 62 gr rounds will serve you well at short range. And if you ever find your self with a BG with in 50 yards shoot center mass forget the head shot stuff. This general guide still holds true in your case. Vool thing is you have an AR you can in with ease swap out any barrel you wish and needs change.
    Attachment 309466
    I think that chart needs the caveat of “YMMV”, because I’ve got a 1:9 twist HBAR that is a tackdriver with 69gr SMK’s...considerably better than lighter weight SMK’s.

    And 40gr bullets do just fine, accuracy-wise, out of a 1:7; I tried some out, accuracy was on par with 62gr M855...
    Last edited by Cuda66; December 29th, 2019 at 01:46 PM.
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  3. #18
    VIP Member Array subhuman's Avatar
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    may call this thing Zeus, just did a 3 shot string out back, it dusky dark out there and I can just make out the yellow target, 3 huge fire balls lit up the back yard while that short barrel thunder echoed down the hollows
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    If it needs to be done, do it.
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  5. #19
    VIP Member Array Smitty901's Avatar
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    Now confuse the issue even more . What chamber are you using .223. 5.56 or WYLDE. Simple .223 was designed to shoot .223. 5.56 was designed to shoot both and it does. The WYLDE was designed to shoot .223 but shoots both better. The difference is not huge in most cases. But when you are search for the most accurate, repeatable groups and what round will provide that. It does make a difference. I own Ar's in all 3 and for the most part they all will do the job .
    If I had time to think and get it and had to bet my life or someone else. My WYLDE with 1 in 8 twist and high quality ( Hornady 68 gr match) or other good 69gr. It will put the hole where it belongs nose to nose or foot ball fields away. And if I ran out of the good stuff it we do just fine with .223 55gr.
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    Yes Taurus really does suck. But in fairness they sure turned it around fast on warranty repair. Time will tell

  6. #20
    VIP Member Array subhuman's Avatar
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    1st 3 hit to the left, 2 clicks 3 more in line with the bull 1 high 2 low , once again shot from a sitting postion with my elbows braced on my knees, I'm calling it good

    If it needs to be done, do it.
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  7. #21
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    Lil bit loud Sub? Those short barrels produce a whole lot of racket. My short x39 would be a beast on nekkid ears. Does the EPS sell cans too?
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  8. #22
    VIP Member Array subhuman's Avatar
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    Quote Originally Posted by svgheartland View Post
    Lil bit loud Sub? Those short barrels produce a whole lot of racket. My short x39 would be a beast on nekkid ears. Does the EPS sell cans too?
    I think he does, never asked, not willing to pay for the privilege
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  9. #23
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    Quote Originally Posted by RBI55 View Post
    The heavier grain bullet does better in a 1:9 twist rate barrel than in a 1:7 twist. So depending on the twist rate of your 10.5" barrel, it's going to do fine or it won't be ideal. A 55 or 62-grain bullet is better in a 1:7 twist barrel than the 75-grain would be.

    I think you have that backwards.
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  10. #24
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    Quote Originally Posted by Rob99VMI04 View Post
    I think you have that backwards.
    Yep, I got it backwards. And yes, it has been a long month.

    I did some research and maybe this will help clarify .223/5.56: (From Chuck Hawks' website)

    "Another peculiar rifling twist story involves the .223 Remington, called the 5.56mm NATO by the military. This cartridge was designed specifically for use with 55 grain spitzer bullets and its twist rate was originally specified as 1:14". This was later tightened to 1:12" for long range shooting, which works very well with bullets weighing 40-60 grains, the usual .22 centerfire bullet weight range.

    Years later, the military decided they needed more penetration, so they increased the normal service cartridge bullet weight to 62 grains and some military cartridges use bullets at heavy as 77 grains. Meanwhile, some hunters could not resist trying their .223 rifles on small deer and they also used heavier bullets, up to about 70 grains.

    The standard 1:12" twist could not properly stabilize these heavy bullets, so the military went to a 1:7" twist, designed to stabilize bullets weighing 62-77 grains. Most manufacturers of AR-15 type civilian rifles followed suit.

    Unfortunately, 1:7" is too fast for frangible varmint bullets, so now we have two "standard" twist rates for .223 rifles: 1:12" for varmint rifles and 1:7" for military type rifles. The latter are often, but not always, stamped "5.56mm."


    He also has a formula for calculating the Twist Rate.

  11. #25
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    My 10.5" 1/7 twist shoots 55 grain fine but the Hornady "Black Rifle 75 grain" are more accurate and hold better groups out to 100 yards (the farthest shots tested). While walking/tracking in the thick woods this last weekend I dropped 4 feral hogs (all within 30 to 75 yards),80 to 200 lbs. no problem. That's the best recommendation I can offer.
    A Wise Man Changes His Mind, but a Fool Never Does

  12. #26
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    I forgot to mention, I also use a 50 yard zero.
    A Wise Man Changes His Mind, but a Fool Never Does

  13. #27
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    sitting on the back porch it took me 5 shots to take 3 20oz water bottles awhile ago with some USA 55 gr FMJ ammo, about 65 yards and I couldn't really see them clearly I was shooting at the see through blurry spots
    If it needs to be done, do it.
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  14. #28
    VIP Member Array subhuman's Avatar
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    I forgot I had this little laser, it came with my Sig 1911 in the case with the other stuff. I'm going to play with it and see if I can't lock it in at around 15-20 yards, that way in the house I can keep my head up and see everything just put it where I want to make a hole, outside light up the reddot for working across the yard

    If it needs to be done, do it.
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