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AR-15 ammo question

Rebel_James
I've got a preban AR-15 A2 H-Bar rifle. Which ammo works best in it, the 55 grain, or 62 grain?

I don't know the rate of barrel twist. I looked in the owners manual and it wasn't there. It is an A2 preban model though.

"If they won't give us good terms, come back and we'll fight it out."
-- Gen. James Longstreet
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Comments

8 comments

Date Votes
  • Tailgunner1954
    Each rifle is different, even if the SN is only 1 apart.
    Try a sample of each and see which one yours prefers before you stock up.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • TRAP55
    RJ, there has been considerable debate here on this. It comes down to the barrels twist rate v/s bullet wieght.Whats the twist rate on your gun?
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  • TRAP55
    I'm sure there are others more informed than me, but my best guess would be 1 in 10 or 9. For the best accuracy i would say the 62grn, but i don't think there would be much difference between the two bullet weights. Search this board for "rate of twist". Some members tell how to determine the twist in your barrel in good detail.I'm sure better than i could here, i'd have to show you! Also, there was a recent post of best bullet weights for each twist rate found in .223 barrels.
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  • gunstosell
    Should be on top of barrel near front sight. It will appear as; 1/8; 1/9 etc.[:o)]quote:Originally posted by TRAP55
    I'm sure there are others more informed than me, but my best guess would be 1 in 10 or 9. For the best accuracy i would say the 62grn, but i don't think there would be much difference between the two bullet weights. Search this board for "rate of twist". Some members tell how to determine the twist in your barrel in good detail.I'm sure better than i could here, i'd have to show you! Also, there was a recent post of best bullet weights for each twist rate found in .223 barrels.
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  • gunstosell
    What do you want? Accuracy, maximum retained energy, both. ??????? More.... I think you will find that there is no one correct answer to your question! It is complex and involves a number of factors besides rate of twist. It boils down to a combination. And, there are many that will work. You should go to ammunition manufactures web sites. Federal, Winchester, Hornady, Remington all have ballistics for their products. You will find the range of weights to go from 40 grains to 75 grains. Each with differing characteristics. These characteristics tell how the particular round performs from 0 to say 500 Yards. You should look at these tables. Once you understand it you will learn. They key to performance is a combination of factors, weight being only one of many. The rate of twist is another. This rate of twist has differing affects on the bullet depending on other factors such as weight, speed, and shape of the bullet, to name a few.[8]quote:Originally posted by Rebel_James
    I've got a preban AR-15 A2 H-Bar rifle. Which ammo works best in it, the 55 grain, or 62 grain?

    I don't know the rate of barrel twist. I looked in the owners manual and it wasn't there. It is an A2 preban model though.

    "If they won't give us good terms, come back and we'll fight it out."
    -- Gen. James Longstreet
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  • prism133
    you can use either weight but for longer barrel life i would consider the 55 grain or even lower which is good for higher muzzel velocity
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  • allechalley
    Not saying they are all marked, but my HBAR is marked on the top of the barrel in front of the forward sight, gives rifle twist rate, mine is 1 in 7, which I'm told is supposed to prefer 62gr. You might also use a cleaning rod with patch. Once you get hte patch snuggly in the barrel mark your rod. It should follow the rifling and turn.
    Measure the length it takes to make one turn. Should get you close to correct number per length of barrel.
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  • TRAP55
    Mine is a 1 in 7 also. I've had the best long range accuracy with a 69grn hpbt. I've had bullets lighter than 55grn disenegrate leaving the barrel, they were the spsx bullets.
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