Recreating 300 blackout brass.

Discussion in 'Reloading' started by tokatee, Oct 22, 2018.

  1. tokatee

    tokatee Well-Known Member

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    Having trouble with remanufactured brass from lc 556. Gun is jamming bad with this brass, is ok with rem., I think it is the neck thickness. Rem.necks measure .010 " , LC. remanufactured measures .014" . Anybody had the same problem? My firearm by the way is a Springfield Saint. Thanks for any replies.
     
  2. Gord0

    Gord0 Well-Known Member

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  3. bigedp51

    bigedp51 Well-Known Member

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    Forming .300 Blackout Brass
    http://www.massreloading.com/300BLK.html

    Step 1 - Case Selection and Inspection
    Don't dive into your brass bucket and start randomly trimming those range pick-ups just yet. If you're going to make your own .300 Blackout cases, the initial parent case selection is very important.

    [​IMG]
    Figure 1 - .300 AAC Blackout Chamber Showing Diameter at the Neck

    You can save yourself quite a bit of time and effort if you use only cases with the proper wall thickness. Take a look at the chamber drawing in Figure 1. Notice that the diameter of the chamber at the location of the case neck is 0.3350". Since the bullet has a maximum diameter of 0.309", that leaves only 0.026" of total space available for the brass. There should be about 0.002" of total clearance around the neck for reliable feeding, so the maximum case wall thickness is about 0.012". Keep in mind that 0.012" leaves almost no room for irregularities in case concentricity, so in reality you're better off with cases that are slightly thinner than this; a 0.0110" to 0.0115" wall thickness is just about perfect.

    Click on the image below to make very large, and look at the case wall thickness minimums.

    Color a few of the problem cases with a black felt tip marker and see where it has worn off after chambering the cases. If they are rubbing on the case body or the shoulder and base of the case the cases may need to be sized with a small base die and have the shoulder bumped back further. If only the necks have rub marks the the necks are too thick.

    [​IMG]


    NOTE, chambers and dies can vary in size and for a semi-auto the case body diameter should be .003 to .005 smaller in diameter than its fired diameter. I size all my bulk once fired Lake City brass the first time with a small base die. And thereafter use a standard die after the cases have been fired in my chamber. The cases were fired in a verity of chambers and you can be dealing with brass spring back after sizing. And this will show up as rub marks on the case body.
     
    Last edited: Oct 23, 2018
    DUSTY NOGGIN likes this.
  4. tokatee

    tokatee Well-Known Member

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  5. bigedp51

    bigedp51 Well-Known Member

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    tokatee

    Nothing you wrote was posted and all that shows are three of my posting quotes and nothing more.