Chrome & Barrel Rifling?

Discussion in 'AR-15 Discussion' started by Triumphman, Oct 10, 2012.

  1. Triumphman

    Triumphman Active Member

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    I know about the ease of cleaning and durability of chrome lining of barrels. My question is, whether the manufacturer, over sizes the barrel bore before they button rifle it, to allow for chrome thickness?
    Or, they just apply the chrome in the bore of a standard barrel, and chrome builds up on the grooves/landings and leaves less rifling, and that's why accuracy is supposably affected with a chrome lined barrel. I'm new to AR's but still learning.
    Del
     
  2. primer1

    primer1 Well-Known Member Supporter

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    Tried Google? I would think they would have to oversized before chroming. The chrome is going to be be at least a couple thousands of an inch thick, multiply times two and the pressures would be too high from the tight bore.
     

  3. bige91603

    bige91603 New Member

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    I had heard from some gentleman who are much wiser than I that they slightly over size it to compensate for the chrome, thus why some say that they are less accurate than non cl. Is this true? Some will agree and others won't
     
  4. primer1

    primer1 Well-Known Member Supporter

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    The people on the AR threads mostly agree the chrome bores are not as accurate.
     
  5. kytowboater

    kytowboater Active Member

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    Ah yes, but does the benefit of the chrome out weigh the negative impact on accuracy??
     
  6. bige91603

    bige91603 New Member

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    It matters what you're using it for, chrome lined is strong and hold up to more use and prolonged use
     
  7. JonM

    JonM Moderator

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    There are schools of thought on this topic. Not all chrome lining is equal. Some is really thin others thicker. The main proboem is that chroming process doesnt leave an even coating on the bore. There are high and low spots but this is due more to the actual care taken to rifle the bore itself than any real flaw in the lining process.

    Take the same bore chrome vs un chrome made on the same day etc. They will shoot the same. The highs and lows left by the chroming process are so small that it wont affect anything. An innacurate barrel is an inaccurate barrel.

    How the barrel is cut, who is cutting it, the technique used, barrel material all that is the real key to accuracy.

    My bcm middy is hammerforged, chrome lined chamber and bore (some barrels only chrome the chamber) and is a sub moa gun out to 300yds.
     
  8. ZeusEcho

    ZeusEcho Member Lifetime Supporter

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    With what ammo might I ask?

    I know you are a damn good shot ;) but I'm not getting close to sub MOA at 100 yards with my BCM hammerforged middy. I've only used Federal 62gr M855 and Remington 55gr 223. Got about 400 rounds through it and it's about 1.5-2 MOA at 100 yards. I was using a 4-9x40 Bushnell Banner scope, bipod, and rear sandbag.
     
  9. hockeyjr1

    hockeyjr1 New Member

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    You problem is your ammo... Try some match stuff and see what you get.. Also if you have a 1/7 twist barrel you can stroll into the 70+ gr bullets which should be much more accurate..
     
  10. JonM

    JonM Moderator

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    69 and 77 grain smk over w748 powder max load from the sierra manual. and ss109 over w748 i use data from hornady 62grain hp loads

    i dont get that with the acog but i do when i put my nightforce nxs f1 for accuracy testing

    you need to handload to get the best out of accuracy. blackhills match ammo is the only thing out there that even resembles what is possible with careful handloads

    55grain fmj sometimes hits 1-1.5 at 100 but 2inches is the norm and thats within the 3moa military standard for an issue rifle with that bullet

    if your testing by holding the gun yourself you need a really good front rest and a good sand bag for the rear. caldwell basic rests are great for that run about 20$ for their elcheapo front rest which is a great one.

    the stock bcm trigger is not a good accuracy one and that holds things back a lot. i dropped in my rra two stage for testing
     
    Last edited: Oct 10, 2012
  11. ZeusEcho

    ZeusEcho Member Lifetime Supporter

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    Thanks guys-I figured it was mostly the ammo.

    I was using a harris bipod, caldwell rear sandbag and a Timney 4lb trigger.

    I can shoot 0.25-0.5 MOA (Federal Sierra Matchking 168gr) with my M700 308 with the x-mark trigger which doesn't feel anywhere near as good as the Timney in the BCM.

    Edit- i would really like to learn reloading. Just too much at the moment so I'll have to stick to buying match grade ammo for now :)
     
    Last edited: Oct 11, 2012