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Thread: Case headstamp and seating depth

  1. #21
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    Just for comparison purposes, there's a chart showing bullet setbacks of my lead bullet handloads and some commercial ammunition. . .
    BulletSetbackSummarya Rounds Pushed Further Into The Case, Post 13.jpg
    . . .and why I described your setbacks as excessive.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Likes (1) :
    Murray (27th April 2022)


  2. #22
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    Ah yes, I remember seeing that one. I know you've already decided on the subject, but I still think there's a book in there with all these graphics you've come up with over the years.

    After thinking it over, it bothers me that I may have gotten the rounds out of order or had other variations in the mix. My new plan is to reload another box exactly as I did before, then go through the measure, chamber, eject cycle all in one shot at the range, but like you did here with top round on a full 7 round mag.

    If I get ambitious, I have some Armscor on hand as well. It's probably not the same as what you have above, but it's as close as I can get to a reference against it.

  3. #23
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    These setback tests can be done safely at home if the firing pin is removed from the test gun. If the FPS won't stay in position, just tape it in place.

    Doing this will avoid the pressure by other shooters at the range to make the firing line safe.

    The data you provided in Post #18 tends to indicate reducing your excessive setback can only come through modifying your reloading procedures. The S & B cases I've measured show they're thick enough to provide a better grip on a jacketed bullet as long as:

    The fired cases are resized to a sufficiently small ID,
    The case mouths are flared as little as possible,
    The case neck expanding plug on your expanding/flaring die is not too large,
    The bullet OD's are large enough to stretch the case mouth during seating for a good grip on the bullet (sensed by the resistance felt in the press handle during seating),
    Little or nothing is done to the case mouth after the bullet is seated.

    Matter of fact, your test handloads don't even need to be primed or filled with powder - they're just dummies to be slingshotted.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Last edited by niemi24s; 30th April 2022 at 16:45.


  4. #24
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    I got out to take measurements a couple of weekends ago and finally got to a little number crunching.

    Methodology: 7-round Tuner Checkmate mags x5, my reloaded S&B cases + Berry's 230gr, each round measured before and after chambering

    Overall average setback: 0.025"
    1st round average (small sample, I know): 0.038"
    7th round average: 0.012"

    Comparing against your chart, I can't say I'm beating factory. There's certainly room for improvement, but overall I suppose I'm happy enough. I may get antsy and try to do better, but it may be time to put the calipers away for a few weeks and do some reloading instead. Or continue sanding down the parkerizing on my slide/frame to keep that 1st 1911 build going before all the rules change.

    As always, I can't say thank you enough. You all keep me improving every time I come here.

  5. #25
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    If by this
    1st round average (small sample, I know): 0.038"
    you mean that the top rounds fed from full 7 round magazines had an average setback of 0.038", then your cases have a lousy grip on their bullets.

    This amount of setback is 31% worse than the worst commercial ammunition I've ever tested. And because the amount of bullet setback suffered decreases as the magazine empties it may explain any muzzle velocity variations you may have experienced. In addition, too much setback can cause feeding problems.

    In an effort to improve your low case grip please post some measurements of the case mouth OD of those Berry's reloads. This is a pretty fiddly measurement and requires the corners of the caliper jaws to be as close as possible to the case mouth. Include the case headstamp with each OD.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Last edited by niemi24s; 30th May 2022 at 09:56.


  6. #26
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    I'll try to get to this as soon as I can. Before my last range trip I went to grab a box of my latest reloads only to find I used them all. That left me with some of my earlier ones. I still have the dies set up, though, so next time I do some reloading, I'll take several measurements throughout the process to get something worthwhile. My RO also noted those earlier reloads were seated far to deep. I'm thinking maybe half a box to my current setup and half with a longer COAL to see if that makes any difference. I've been getting quite a few malfunctions lately and suspect how exactly I'm setting up my reloads anyway.

  7. #27
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    oh boy, time for my regular slice of humble pie. I thought a good calibration would be to test setbacks on factory ammo in the same gun and mags, as well as trying a longer COAL on my bullets to begin with. Which got me comparing results against my original.

    To start with, I misread my original measurements and was off by a decimal. The original above should have been:
    0.0025" average setback
    0.0038" 1st round setback
    0.0012" 7th round

    meaning if I read it right, I was doing okay to begin with. However, I noticed a lot of malfunctions I won't go into until I get more experience with the longer rounds, maybe some fresh mag springs. So why not try something like 1.268"? I also did a rough measure of the brass throughout loading. You're right, those are hard to take and I ended up making several measurements + guesstimating the numbers at around a minimally flared case mouth at darned near ~0.472" with a ~0.01" thick case, which should be putting me spot on against a 0.452" bullet.

    New results:

    Factory ammo (brand "A"), 3 mags (so the averages don't mean a whole lot, but here goes):
    0.0073" average
    0.0233" 1st round average (skewed heavily by test #3 coming in at 0.036")
    0.0011" 7th round average

    Murcor (my reloads) S&B brass, Berry's 230, 1.268" COAL
    0.0008" average
    0.0016" 1st round
    -0.0002" 7th round

    I'm attributing the apparent slight growth in some rounds to my caliper skills, or if I'm being generous, the 85 degree weather causing expansion during testing.

    Unless someone spots a big flaw here, I think I might have gotten this one and even tightened up my setbacks a touch in the process. Now that things look good again, Cabela's restocked the 0.451" X-Treme bullets I was using early on at $20 cheaper per box of 500, so naturally I'll be back to the drawing board again soon.

  8. #28
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    Only issue I can see now is your ability to either read, record or report whatever instrument you use to take these measurements.

    Happy shooting.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  9. #29
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    I'd say I'll work on that, but I've reached the age where that's unlikely. Thanks for all the help thinking through the problem. It still helped me improve.

  10. #30
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    When I first started loading for 9mm and people talking about sorting cases I did a chrono test on that. I loaded up 5 different brands of cases and measured each load on my scale and one batch of random cases. And as a control group I just reached in my can of loads I had made before with no care of headstamp and didn't weigh the loads. I let my powder measure do it. What I found there was not enough difference in them to worry about. I plunk stuff at 25 yards. I am not a precision shooter so it wasn't important. If you are a super shooter and doing bullseye shooting you might see a difference. For me if it hits the can I am good. If I was getting setback like the picture I would be worried.
    Ron

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