9mm sizing? Possibly over crimped?

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  • grunt soldier

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    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!
     

    sloughfoot

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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.....
     

    grunt soldier

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    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
     

    sloughfoot

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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.
     

    Bennettjh

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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.
     

    ScouT6a

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    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.
     

    shibumiseeker

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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.
     

    rvb

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    BTW, I have never measured the amount of crimp.

    Like sloughfoot, I don't measure crimp. my check is different, however. "crimp" on a straightwall pistol cartridge that headspaces off the case mouth is a misnomer. you aren't trying to "pinch" the bullet, you are simply removing the bell. I hold a straight edge along the bullet against a lamp and look that the case mouth is straight, not crimped in, not belled out, just straight. then I pull a bullet and make sure there is no significant crimp ring. you might still see a hint of a ring on the bullet, but anything you can feel means you have too much..

    -rvb
     

    grunt soldier

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    Well I pulled several in the process of and they definitely have a ring around them and you can catch it with your finger nail. It's not like a groove cut in the plating but there is a small lip
     

    rvb

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    Well I pulled several in the process of and they definitely have a ring around them and you can catch it with your finger nail. It's not like a groove cut in the plating but there is a small lip

    if you are shooting plated, definitely don't over crimp. I've never used plated, but I've seen the problem many times where someone over crimps and it cuts/weakens the plating, causing all kinds of inconsistency... sometimes even causing the plating to separate in extreme cases. when ever someone asks for help with poor groups and they are loading a plated, that's the first thing I check. jacketed and lead seem a lot more forgiving in that regard.

    -rvb
     

    BGDave

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    Like sloughfoot, I don't measure crimp. my check is different, however. "crimp" on a straightwall pistol cartridge that headspaces off the case mouth is a misnomer. you aren't trying to "pinch" the bullet, you are simply removing the bell. I hold a straight edge along the bullet against a lamp and look that the case mouth is straight, not crimped in, not belled out, just straight. then I pull a bullet and make sure there is no significant crimp ring. you might still see a hint of a ring on the bullet, but anything you can feel means you have too much..

    -rvb
    This right here. Quick and dirty. I can't even remember who showed me this. (pre-internet things were harder) But it works very well.
     

    grunt soldier

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    Well. I just ran 100 through a couple glocks. My zev tech did not like them. My factory glock liked about 3/4ths of them. Probably a sizing issue as they were lite strikes it appears.

    Ran 50 rounds of American eagle 124gr fmj through each pistol and they were 100 percent.

    I'm running 5.4 gr of longshot. Coal of 1.125 with winchester primers. The last batch I chrono'ed at 1100 fps.

    Accuracy was high. So as RVb states my crimp might be a bit too heavy.
     

    grunt soldier

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    They weren't horrible. Accuracy wise but definitely some fliers that I didn't have with the factory and it was very solid for about 12-15 yards.

    The part I enjoyed most was my factory glock barrel was much more accurate than my storm lake barrel lol.

    Here is the best pic I could get. This one almost looks grooved.

     

    rvb

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    Well. I just ran 100 through a couple glocks. My zev tech did not like them. My factory glock liked about 3/4ths of them. Probably a sizing issue as they were lite strikes it appears.

    sizing shouldn't affect primer ignition. make sure those primers are fully seated. primer seat depth is adjustable on the 1050, right? Make sure its seating them solidly.

    I'm running 5.4 gr of longshot. Coal of 1.125 with winchester primers. The last batch I chrono'ed at 1100 fps.

    Accuracy was high. So as RVb states my crimp might be a bit too heavy.

    what was std dev? with a good load you should be getting single digit std dev. when you say "accuracy was high," do you mean poor accuracy? (most folks mean good accuracy when they mention high degree of accuracy)...

    set the crimp as I mentioned, seat those primers fully (ok to crush them a little), and see how it goes.

    -rvb

    -rvb
     
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