Help wanted: Problem with trimming 9mm

Discussion in 'Ammunition & Reloading' started by Shopfox, Feb 7, 2020.

  1. Shopfox

    Shopfox Well-Known Member Supporter

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    Same manufacturer, but doubtful same lots.
     
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  2. Shopfox

    Shopfox Well-Known Member Supporter

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    I went back through the brass and belled the case mouths. Afterwards, tried trimming, then checked headstamps. I was wrong earlier. There was a mix of brass. The S&B still couldn't be trimmed. At least it narrows it down to a brass issue.
     
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  3. Oldoutlaw

    Oldoutlaw Well-Known Member Supporter

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    Very common to see. Different mfrs have different brass and different specs. Also makes some difference if you fire a box of rounds through two different guns. Chambers have tolerances that could effect the case fire forming of the brass.
     
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  4. oO_Rogue_Oo

    oO_Rogue_Oo Well-Known Member

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    I would think it would be pointless to try trimming after belling the case mouth.
    The bell would tend to make the case shorter so I can't see that the trimmer would even reach the case.

    Sort your cases into lots. Inspecting them, paying close attention to the web area of the case; the goal being to sort them into lots of the same internal volume. This will help keep pressures consistent. Then inspect the the flash holes for consistency. Be sure to use the same primers when loading. When putting a bell in the case mouth take care to be consistent; same when crimping. You want the most consistent neck tension you can get for the same reasons as above ......... consistent pressure = consistent velocity. If you really want to go wild; weigh and sort your bullets. Weigh every powder charge. Use a powder that uses the most case volume. Some people will fill any empty space in the case with Cream of Wheat; I prefer cotton. The less air space in the case the more consistent the powder burn will be. In between all this comes seating depth; I usually start at or near max and back off in .002 increments until I find the sweet spot. Normally it will be close to max, maybe even a little beyond. All depends on the barrel / chamber. Inspect your fired brass while working up the load; there are a lot of potential clues there. Pay attention to the condition of the fired primers, look for extractor marks, look at the case mouth. Pay attention to where your brass is ejecting; how far, where, is it consistent etc. Some but not necessarily all of these things will produce results. Every gun is a little different. Once you learn what your gun likes you can focus there and not bother with what's left.
     
  5. Dakota1

    Dakota1 Well-Known Member

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    First I've ever heard of trimming 9mm cases - been reloading them & shooting them in Glocks & Uzis for years.
     
  6. oO_Rogue_Oo

    oO_Rogue_Oo Well-Known Member

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    Yeah, not exactly what you would call common practice. I would imagine you'd see more variation from lot to lot and brand to brand than you would from firing. But; if your looking for max consistency I could see potential benefit. I've never trimmed mine but I have sorted them.
     
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  7. JTJ

    JTJ Well-Known Member Supporter

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    I have trimmed 9mm brass and did not run into that problem. Did you mike your mandrel?
     
  8. Shopfox

    Shopfox Well-Known Member Supporter

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    Some were fired by me, others were range pickups, that's a big part in the "starting variability".
     
  9. Oldoutlaw

    Oldoutlaw Well-Known Member Supporter

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    Oh yea! It certainly is.
     
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  10. Caveman Jim

    Caveman Jim Well-Known Member

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    Or 40S&W
     
  11. Caveman Jim

    Caveman Jim Well-Known Member

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    Good luck with your quest.
     
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  12. Caveman Jim

    Caveman Jim Well-Known Member

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    No but you could call yourself Iowa Skinny...:p:D:p:D
     
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  13. Oldoutlaw

    Oldoutlaw Well-Known Member Supporter

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    UH, no, he can't.
     
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  14. OLD Ron

    OLD Ron Well-Known Member

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    Can just feel the luv here !
    :p
     
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  15. Shopfox

    Shopfox Well-Known Member Supporter

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    I did check the mandrel on the trimmer iirc, it was either .348 or .350,
     
  16. Shopfox

    Shopfox Well-Known Member Supporter

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    Quick update: I measured and the S&B brass is thicker than the other brass. That looks to be the source of the tightness.
     
  17. partdeux

    partdeux Well-Known Member Supporter

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    if you're looking for that level of accuracy and you're using range brass? Me thinks you'd be much better served with NEW brass that you actually keep track of how many times it's fired. 9mm is not known to be an overly accurate round to begin with. There are much better choices to go with
     
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  18. oO_Rogue_Oo

    oO_Rogue_Oo Well-Known Member

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    You work with what you have and maximize it's potential.
     
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  19. Shopfox

    Shopfox Well-Known Member Supporter

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    I'll turn on the 1x fired brass generator this afternoon. Point taken on consistent brass of known origin. 15814532843525764174134503781176.jpg
     
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  20. Shopfox

    Shopfox Well-Known Member Supporter

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    Once fired WIN 9mm brass deprimed, wet tumbled, and ready for resizing, and processing... 1581472806197431112999661697962.jpg
     
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