Reload OAL Inconsistent

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  • Rating - 100%
    8   0   0
    Jan 18, 2009
    2,169
    113
    SE Indy
    Just a question for reloaders. How much varying OAL do you experience on your set up. For instance today loading some 10mm and set up for 1.250 OAL. I may get a few at 1.250 then1.259 then a few at 1.245 I can never get a reliable consistent OAL.
    Plus or minus .10 one way or the other.
    I never use any that come out shorter that .10 of my goal for over pressure concerns. Is this even a big deal. They seem to all shoot fine never had a failure in 5 years. Just looking for utter consistently

    Thanks everyone
     

    tsm

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    1   0   0
    Feb 1, 2013
    857
    93
    Allen county
    Variations in the bullet’s ogive (are you loading hollow points?) combined with a die seating stem that’s a poor match to that ogive can cause that. Cases could be different lengths, your press setup could be inconsistent (loose), all kinds of things. As these guys said, what’s your setup you’re loading on?
     

    DadSmith

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    1   0   0
    Oct 21, 2018
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    Ripley County
    If using different brand cases that can cause it to jump around, also have you trimmed cases so they are all the same length? If mixed brass is used try sorting out around 20 pieces trim them then load them. They should be within 0.001-0.002 or close to that of the OAL you want. Mixed untrimmed brass will have you all over the place.
     

    jason867

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    Jan 7, 2009
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    New Castle
    If it's just plinking ammo and you're not loading close to max charges, not compressing powder, and not seating super short OAL's, then i would shoot them all without worry. They would most likely shoot better than you and the gun anyway.

    If however, you are an accurate shooter with an accurate gun/optics, or are loading hot stuff, or are using super short OAL's, or loading self-defense or hunting ammo, then you would need them more consistent.

    What press?
    What dies?
    Solidly mounted to a sturdy bench?
    What bullet?
    Powder charge? Also, is it compressed?
    Are your dies snug/tight?
    How much neck tension? Bullets tightly held by the brass or is it easy to push them in?
    Is your technique consistent? Specifically operating the press handle.
    Are you camming over the press or hitting the travel stops each time?
    Are you measuring them the same and consistently?
    Batteries low in your micrometer?

    Lots of things can cause variation in OAL. Might be more than one thing.
     

    gmcttr

    Grandmaster
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    12   0   0
    May 22, 2013
    8,596
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    Columbus
    ...For instance today loading some 10mm and set up for 1.250 OAL. I may get a few at 1.250 then1.259 then a few at 1.245 I can never get a reliable consistent OAL.
    Plus or minus .10 one way or the other...

    FWIW, 1.259-1.245=0.014". That's a MUCH smaller variation than "plus or minus .10 one way or the other" which would be 0.20" total variation.
     
    Rating - 100%
    8   0   0
    Jan 18, 2009
    2,169
    113
    SE Indy
    If it's just plinking ammo and you're not loading close to max charges, not compressing powder, and not seating super short OAL's, then i would shoot them all without worry. They would most likely shoot better than you and the gun anyway.

    If however, you are an accurate shooter with an accurate gun/optics, or are loading hot stuff, or are using super short OAL's, or loading self-defense or hunting ammo, then you would need them more consistent.

    What press?
    What dies?
    Solidly mounted to a sturdy bench?
    What bullet?
    Powder charge? Also, is it compressed?
    Are your dies snug/tight?
    How much neck tension? Bullets tightly held by the brass or is it easy to push them in?
    Is your technique consistent? Specifically operating the press handle.
    Are you camming over the press or hitting the travel stops each time?
    Are you measuring them the same and consistently?
    Batteries low in your micrometer?

    Lots of things can cause variation in OAL. Might be more than one thing.
    Thanks. I guess it may be a combination of all those. They do shoot fine. Just looking for more consistent results.
    Thanks for the reply
     

    jason867

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    112   0   0
    Jan 7, 2009
    1,451
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    New Castle
    You're welcome.

    Start with one thing and check and then double check that there's no issues with it. Then when you're absolutely sure that one thing isn't causing problems, move on to the next potential problem area...
     
    Rating - 100%
    8   0   0
    Jan 18, 2009
    2,169
    113
    SE Indy
    Its just a Lee single stage press using Lee and RCBS Dies.and a cheap digital micrometer this particular batch was all new Starline brass. and Hornady XTP 155G HPs.
    Thanks for all the pointers everyone.
     
    Rating - 100%
    8   0   0
    Jan 18, 2009
    2,169
    113
    SE Indy
    You're welcome.

    Start with one thing and check and then double check that there's no issues with it. Then when you're absolutely sure that one thing isn't causing problems, move on to the next potential problem area...
    Will do. BTW my wife is from New Castle. Went to Blue River HS. Nice little town. I like it there.
    Thanks again
     

    tsm

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    1   0   0
    Feb 1, 2013
    857
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    Allen county
    Measure the lengths of 10 or 20 of your Hornady XTPs and see how much they vary. Montana Gold Bullet makes 9mm HP bullets with a very similar profile and I’ve seen those vary in a batch by as much as you’re reporting; I’ve just never used Hornady bullets to know whether they do as well, or are more consistent.
     
    Rating - 100%
    8   0   0
    Jan 18, 2009
    2,169
    113
    SE Indy
    Measure the lengths of 10 or 20 of your Hornady XTPs and see how much they vary. Montana Gold Bullet makes 9mm HP bullets with a very similar profile and I’ve seen those vary in a batch by as much as you’re reporting; I’ve just never used Hornady bullets to know whether they do as well, or are more consistent.
    That is a great idea. Thanks
     

    XtremeVel

    Master
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    21   0   0
    Feb 2, 2010
    2,380
    48
    Fort Wayne
    A few above mentioned case lengths. I don’t understand how that can have a part in varying OAL measurements. Case lengths that vary can play a part in inconsistent crimp, but I don’t see how it can impact the overall measurement.

    I’d first check to make sure you aren’t measuring over inconsistent seated primers. Make sure you don’t have primers that are seated high.

    if primers look good , and assuming you have the seater plug/stem snug along with the die body, I’d look like mentioned above at the bullet profile. Pay special attention to the area between where your seating plug or stem makes contact with the bullet and the part your calipers are measuring over. If you can see inconsistencies in that area, you’ll obviously will see inconsistencies when measuring .
     

    jason867

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    112   0   0
    Jan 7, 2009
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    New Castle
    I should've thought of the primer seating issue.

    They should be seated just a hair below flush, but not crushed either.

    A high primer will mess with your OAL measurements, and increase your risk of slam fires.
     
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