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  1. #1

    9mm sizing? Possibly over crimped?

    Ok so I switched over to 223 on my press and got to double checking my 9mm and it appears my Lee Factory crimp die may have been improperly set (or it could have been right but I'm nervous now and don't want to loose 1k of components).

    I'm loading Rocky Mountain reloading 124gr plated bullets spec size is supposed to be .3565

    Mixed cases.

    Loading on a dillon 1050.

    So I go and check with my Mic and all my manuals say it should be .380 or so to be SAAMI specs. So I start checking mine and it's all mic'ing at .3750-.3770

    So I also checked a lot of my factory ammo ranging from 115-147gr, All FMJ and Hollow points and they all mic'ed around .3730 (which isn't what my manuals are saying it should be lol)

    I'm basically concerned that they were over crimped and aren't safe to shoot now. I don't really want to pull 1000 rounds and start over but I also don't want to blow any of my pistols up either lol.

    All my previous 9mm reloads had no issues and unfortunately are used up so nothing else to mic for comparison.

    So my question I guess is what is your ammo mic'ing at right at the crimp on the case? Especially if you load something similar. It just seems the manuals say one thing and factory ammo and my ammo is showing something else.

    (I'm sure I'll get all kinds of answers and responses to not take the chance on it etc but I'm also curious now to see what everyone else is at!!) Maybe I'll just buy a hi-point and run a couple hundred rounds through it and see what happens lol)

    Thanks in advance for any answers!
    Hello

  2. #2
    Grandmaster sloughfoot's Avatar
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    Pull the barrel out of your pistol and chamber check your ammo. The only possible problem with an over crimp is that the cartridge goes too deep in the chamber. I have never seen it happen, but doing this should put your mind at ease.

    BTW, I have never measured the amount of crimp. I drop check in a barrel and tighten crimp until there is no drag when dropping it in. I don't know what you think what catastrophic thing might happen with a tight crimp.....
    Red Fire 372

  3. #3
    Marksman
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    I just checked my reloads and they measured exactly the same as yours. I have mixed brass with 124 gr Rainier hp and Berry's rn.

  4. #4
    Thank you both for the replies. I appreciate it.

    And slough according to the intrawebs (invented by Al Gore) it will create excess pressure causing a catastrophic failure and possible explosion turning my pistols into a handheld claymore! (Obviously some sarvasm mixed in there but some not)

    I chamber checked every 10th round and all passed in the process. Checked more tonight and they seat same as factory ammo
    Hello

  5. #5
    Grandmaster Bennettjh's Avatar
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    I'll check mine in a minute. BRB.
    It's ok! I'm an INGO member!

    Todd Young (R-IN)
    https://www.young.senate.gov/content/contact-senator

    Joe Donnelly (D-IN)
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  6. #6
    Grandmaster sloughfoot's Avatar
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    Yeah, I have heard the internet wisdom. What causes pressure is getting that bullet moving and jammed into the lands and moving down the barrel. That brass neck opened up to chamber dimension long before all that craziness started happening. Tight crimp can help achieve consistent start pressure, but I don't see any way for it to contribute to excessive pressure. It just does not take that much pressure to get the malleable brass to release its grip on the bullet. A couple thousand PSI compared to thousands of PSI developed overall.

    Shoot your ammo with confidence.
    Red Fire 372

  7. #7
    Grandmaster Bennettjh's Avatar
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    I checked a couple rounds. Mixed brass, all measured .3750-.3755. I've shot hundreds of rounds just like them with no issues.

    I'd say shoot with confidence.
    It's ok! I'm an INGO member!

    Todd Young (R-IN)
    https://www.young.senate.gov/content/contact-senator

    Joe Donnelly (D-IN)
    http://www.donnelly.senate.gov/contact/email-joe

    Find your U.S. Rep
    http://www.house.gov/representatives/find/

    /l ,[____],
    l---L -OlllllllO-
    ()_)-()_)-o-)_)

  8. #8
    This thread got me curious, so I grabbed my micrometer and a handful of my hand loaded 9mm rounds. They are 124 grain LRN cast by me, in a Lee six cavity mold with wheel weights. Loaded with Dillon dies on a 550.
    All measured .377" They chamber fine and fire great in my CZ, Beretta, Hi Power, Ruger and 9mm AR pistol.
    All skill is in vain when an angel pisses in the flintlock of your musket.

  9. #9
    Plinker
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    The .380 is the maximum dimension, so you are just about perfect at .003-.005 below that.

  10. #10
    Grandmaster shibumiseeker's Avatar
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    It will be fine. Variations in case wall thickness will cause differences in crimp tightness greater than that. .380 is the maximum.

    Really, 9mm is one of the most forgiving rounds to work with. All modern guns are capable of handling +P and a lot are capable of a regular diet of +P+. While there is no SAAMI spec for +P+, most NATO 9mm is loaded well beyond SAAMI spec so modern guns are built to handle that. With 9mm you could just about swage the case and bullet together and still not do any damage. About the only time I get that picky is when I am loading my nuclear 10mm rounds since they are already overpressure. As long as they chamber correctly they are good to go.

    IWTFM Eternal vigilance is the price of chickens. JFC advocate.

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