223/5.56

223/5.56

This is a discussion on 223/5.56 within the Reloading forums, part of the Defensive Ammunition & Ballistics category; Well, I finally got a chance to get out and chrono my new loads for 223/5.56. I haven’t been up to the range lately because ...

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Thread: 223/5.56

  1. #1
    Senior Member Array BlackJack's Avatar
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    223/5.56

    Well, I finally got a chance to get out and chrono my new loads for 223/5.56. I haven’t been up to the range lately because of a combination of my travel schedule and the weather. The primary reason that I am looking for a new load is that I have moved from the Lee Pro Auto Disk powder measure to the Dillon powder measure which allows me to better make small adjustments in the powder charge.

    I started at 24.7gr of Ramshot TAC and went up to 26.3 in increments of .4gr. While 26.3gr is listed by Western Powder as the max load for this bullet in 5.56, I am not seeing any signs of over pressure in the cases and I am seeing velocities that are about 200 fps below the velocity listed for that charge in Western’s load data. Of course, their test bbl is listed as 24” with a 1:7 twist while mine is 16” with a 1:9 twist (I have no idea what difference the twist rate or bbl length make in the pressure). The reason that I started at 24.7 is because I have already been using 24.3 and have not been getting the consistency that I have been looking for (average SD of about 30, or maybe a tad bit more). In all cases I loaded the Sierra 65gr GameKing in used Lake City brass from Federal XM193 With CCI SRPrimers. These are NOT once fired brass. They have probably been loaded anywhere between 3 and 6 times. My COAL was 2.255”

    I loaded 20 rounds at each charge weight, for a total of 100 rounds, and all loading was done on a Dillon 550C with the Dillon powder measure. I shot these in 10 round strings because my chrono records in 10 round strings.

    For the lower 3 charges I got velocity ranges and SD that just were not in the range that I was looking for. While a couple of them did give me an SD of under 20, and one of them was even down to 15.93, the other 10 round strings were at 31.46 and 20.37. As a result I am going to drop those loads from consideration, at least for now.

    The last two that did look good to me were 25.9 and 26.3gr of powder.

    At 25.9gr of powder I got the following for the first 10 round string:
    Average Vel of 2921
    ES of 52.83
    SD of 16.09

    For the second 10 round string. I got the following:
    Average Vel of 2908
    ES of 51.29
    SD of 17.6

    When I combine them and use what I will refer to as the “Tangle” method I get the following:
    Average Vel of 2914
    ES of 72
    SD of 17.24



    At 26.3gr of powder I got the following for the first 10 round string:
    Average Vel of 2979
    ES of 59.45
    SD of 17.74

    For the second 10 round string. I got the following (caveat… I only had 9 rounds for this because one of them errored out on the chrono):
    Average Vel of 2996
    ES of 51.95
    SD of 16.3

    When I combine then and use the “Tangle” method I get the following (caveat… I only had 19 rounds for this because one of them errored out on the chrono):
    Average Vel of 2987
    ES of 62
    SD of 18.42

    Since both of these loads gave me “relatively” consistent velocities with a SD of less than 20 from the combined strings, I am going to focus on these loads and see what I can do (SD of less than 20 is what I am looking for (I would love to see it get down into the lower teens, but am not sure whether or not that is a realistic expectation for 5.56). I am planning on loading up and testing an additional 50 rounds of each of these and see if I can identify one as more consistent than the other. Depending on what I get, I might try varying the seating depth, and therefore the COAL to see how much of a difference that makes. I didn’t test for group size on this range trip because I was only able to shoot at about 20 yards, but next time, I will also be shooting for group size.
    darbo and Chuck R. like this.

  2. #2
    Distinguished Member Array FLSlim's Avatar
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    Nice report. I've never used TAC, but it could be used down the road and reports like this are always useful.
    Chose a weapon that goes bang EVERY time!

  3. #3
    VIP Member Array Chuck R.'s Avatar
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    I load TAC under the HORN 62 grn FMJ for my 3Gun load, it meters very well in both my Dillon and Harrell's measures.

    25.4, FC brass, WSR Primer, get's me in 2847 at 43 degrees out of a 16" barrel. Can go higher based on pressure signs, but it's about 1 MOA and more pressure = more recoil. TAC has to be stepped on a little to give good chrono stats. I'd be careful of getting too close to max in the cooler weather, because while TAC is one of the better ball powders temp sensitivity wise, it's not as good as some of the extruded powders like Varget. All of my precision and coyote loads use Varget for that reason.

    Honestly IMHO groups trump stats until you hit the 500 yd mark when the large SDs start to show in stringing. Also IMHO achieving small SDs are a lot easier in a longer barrel
    homo homini lupus est

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  5. #4
    Senior Member Array BlackJack's Avatar
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    Quote Originally Posted by Chuck R. View Post
    Honestly IMHO groups trump stats until you hit the 500 yd mark when the large SDs start to show in stringing. Also IMHO achieving small SDs are a lot easier in a longer barrel
    Very good feedback, especially for me since I do not shoot beyond about 300 yards these days.

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