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Thread: tight chamber test using a live cartridge.

  1. #11
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    If the chamber was in spec according the correct design, not some wider tolerance used to save money, there wouldn't be any reliability issues. The point is that a casing, brass or steel, is not made to a tight enough tolerance to use for gauging a chamber.

    Quote Originally Posted by kal View Post
    OK but why would a chamber difference of a couple thousandths of an inch dictate extraction reliablity so long as the chamber dimensions are within tolerances?

    If a steel cased cartridge doesn't "spring back" the way brass does, then wouldn't there be no difference between a "tight" chamber and a "correct" chamber in terms of extraction? Consider in both chambers, that the casing would be formed into the shape of the chamber and not able toretract like brass, therefore having no difference in extraction because the surface tension of the spent steel casing against the chamber walls would theoretically be the same.

  2. #12
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    I reference this test frequently,so Im probably the dumb redneck responsible for it being mentioned here the most.
    Here is a snip from one of my posts:

    "you can try a little test I used a few years ago with my tight chambered Armalites in selecting ammo.
    Remove the upper from the lower.Remove the BCG,and clean the chamber and make sure its dry.Then point the muzzle at the ground.Take one of the unfired cartridges from the same lot your having issues with and drop it in the chamber.Apply a bit of pressure on the case head with your thumb or finger to fully seat the cartridge.Once that is done tip the muzzle upwards.If the round drops out of the chamber,repeat using several of the rounds.If the cartridge sticks,knock it out with a cleaning rod and check the ogive of the bullet for rifling and/or leade marks.
    Thats a pretty quick little redneck test to see if the chamber is short and the ammo is suspect.
    If the chamber is short you will either have to stay with .223 Rem ammo.In some cases even .223 Rem can cause issues,classic example would be Wolf as that ammo is loaded long and has a ogive on the bullet that is further foward than most(per Wolf and my personal experience) which will effectively jam the bullet in the short leade and pop primers."

    Im pretty sure this is not a documented test or a valid industry standard type test used by professionals.It is basically something to use in the field if there is a pressure/popped primers type issue that does come about with a questionable rifle or ammo.
    This little redneck test is to see if the chamber has a short "leade" or if the ammo is out of spec causing the bullet ogive to be forced into the rifling causing pressure issues such as blown primers.In my experience the problem is 99% of the time a short leade .223 Rem chamber that is to blame.
    It has nothing to do with the chamber width,how the chamber actually headspaces or how tight or loose a properly sized cartridge case fits in the chamber.
    Whether or not its a valid test or not,all I can say is Ive used to select ammo per batch for a tight chambered AR that would blow primers all day long with different brands/loads.That said everyone of my AR's have proper spec'd chambers from known quality sources...so they can pass the little redneck test with any 5.56 NATO,Wolf and heavy OTM's etc..
    If you want a better verification method then buy one of Ned's chamber gauges...it will tell you real fast if the leade is cut to 5.56 NATO spec..Then have it reamed to spec. using Ned's 5.56 reamer.
    HTH
    Glock Certified Armorer
    Armed Protective Services II

  3. #13
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    Reaming a chrome lined chamber?

    If you have a milspec style barrel wouldn't reaming an out of spec chamber remove the chrome lining? I always see people say to just ream the chamber, but what about this? Couldn't it cause flaking to propagate from the edges of the reamed spots in the chrome or result in uneven fouling or accelerated leade erosion?

  4. #14
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    Quote Originally Posted by VelveteenMole View Post
    If you have a milspec style barrel wouldn't reaming an out of spec chamber remove the chrome lining?
    Whats your other option with a chamber that is too tight?
    Stick


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  5. #15
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    I reference this test frequently,so Im probably the dumb redneck responsible for it being mentioned here the most.
    Here is a snip from one of my posts:
    I had no idea this test was supposed to figure out the leade.

    I thought it was to determine the tolerances of the chamber wall from base to shoulder.

    so when some say you might have a tight chamber, they're really talking about the freebore/leade and not the chamber wall from base to shoulder?
    Last edited by kal; 11-21-10 at 02:19.

  6. #16
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    Quote Originally Posted by Stickman View Post
    Whats your other option with a chamber that is too tight?
    New barrel?

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