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Thread: What is acceptable oal variance

  1. #1
    Join Date
    Dec 2018
    Location
    Wyoming
    Posts
    5

    What is acceptable oal variance

    Hi yall, I'm fairly new to reloading and have dabbled into some pistol loads. Rifle to come. I've searched the internet and have yet to have found a solid answer to this.

    When reloading 9mm on my co-ax press with Lee dies (I know they aren't the most precise but to learn they do ok). I'm aiming for 1.142 as the desired oal. I come up with the oal that is + or - .005. Some are the same. Here is what I measure from round to round: 1.142, 1.138, 1.141, 1.139, 1.142, 1.137, 1.141........

    Are these acceptable variances or am I messing something up and they should all be the same? I've tried to be consistent with the amount of pressure I put on the press when seating. Not sure how much this could effect anything as .005 + or - is a extremely small measurement.

    Any thoughts, input, or tips would be appreciated.

  2. #2
    Join Date
    Jul 2016
    Location
    Albany, OR
    Posts
    180
    Quote Originally Posted by Cruschem View Post
    Hi yall, I'm fairly new to reloading and have dabbled into some pistol loads. Rifle to come. I've searched the internet and have yet to have found a solid answer to this.

    When reloading 9mm on my co-ax press with Lee dies (I know they aren't the most precise but to learn they do ok). I'm aiming for 1.142 as the desired oal. I come up with the oal that is + or - .005. Some are the same. Here is what I measure from round to round: 1.142, 1.138, 1.141, 1.139, 1.142, 1.137, 1.141........

    Are these acceptable variances or am I messing something up and they should all be the same? I've tried to be consistent with the amount of pressure I put on the press when seating. Not sure how much this could effect anything as .005 + or - is a extremely small measurement.

    Any thoughts, input, or tips would be appreciated.
    The first thing to do is examine how you're measuring them. Can you set the round and your caliper down, pick them up and immediately get the same reading? (It doesn't count if you keep measuring until you get the number you had last time.) Measuring tip-to-tail is typically not very accurate, so most will use some manner of bullet comparator to make a measurement to a more reliable datum along the ogive of the bullet. A match seater will seat a bullet straighter and result in less measured variation. Finally, the quality of the bullet will change your results - low quality bullets vary more than match-grade bullets. (Try measuring some bullets all by themselves.)

    Measuring pistol bullets (especially if they're not jacketed), seated with a regular die, I'd say you're doing fine.

    For rifle, with a good seater and quality bullets, you can get everything within 0.002" without extraordinary effort.

    GsT

  3. #3
    Join Date
    Mar 2005
    Location
    A pleasant place, Missouri
    Posts
    571

    questions for you

    What type of firearm are you loading for? Just one or several different ones.
    What type of bullet are you using? Cast or jacketed? Bullet point style?
    Are you taper crimping?
    Centerfire

  4. #4
    Join Date
    Feb 2004
    Location
    Mi
    Posts
    236
    Handgun bullets, especially cast bullets often are quite inconsistent in OAL. Measure a few from base to tip and I suspect you will find your culprit. Base to ogive distance is held to a tighter tolerance. Pistol dies often come with 2 seating plugs, 1 for flat/truncated bullets 1 for round nose. The plug must fit the bullet ogive or you will come up with a very inconsistent COL. Use a plug designed for RN with a truncated/HP bullet style and you wont get 2 COL's to match. Lee should/might offer a plug to fit your bullet. I would call and talk to them

  5. #5
    Join Date
    Dec 2018
    Location
    Wyoming
    Posts
    5
    Quote Originally Posted by Centerfire View Post
    What type of firearm are you loading for? Just one or several different ones.
    What type of bullet are you using? Cast or jacketed? Bullet point style?
    Are you taper crimping?
    Centerfire
    Sorry for the late response. I am currently loading for dan Wesson valor 45 acp, but have everything I need to do 9mm, 223, and 7 mag as well. I am using 230 gr fmj armscor bullets for the 45. They are just a standard round nose for target shooting. I have been taper crimping.

    I've been able to dial it in a little more today and was able to maintain the oal with in .002. (Measuring from base to tip as I dont have a comparator) Was able to do this by setting the press up again. Not sure what I did different from last time. Kind of strange. In the pursuit of excellence I will figure this out someday

    I thank everyone for the responses so far

  6. #6
    Join Date
    Feb 2003
    Location
    Tennessee
    Posts
    5,096
    Seating a bullet with the typical seater if a fairly simple deal. The results will be the same distance from where the seater touches the bullet to the base of the case on every round. Doesn't matter what you measure...the only thing that matters is how well it shoots.

  7. #7
    Join Date
    Jul 2007
    Location
    S.E. MI
    Posts
    2,148
    Those thousands are not going to matter. Those numbers can be a bane to a brain.....needles are easier on your eyes...
    Reliable function of pistol matters more. If ya can't load the round into the chamber. OAL really does not matter.
    And as the round moves up the magazine or around the cylinder things move a lot....and like everyone pointed out....pistol bullets and their shapes are all over the place.

    But, really in any shooting sport. It's what makes ya comfortable. That little bit of doubt (is that correct?)will wreck a good day at the range.
    I got a stomach bug today. And ruined the little bit of concentration that I had.....
    Last week, I was hitting 6 plates in 3-4.xxx sec. Today, I actually had 2 15 sec. strings.....still can't believe I used 10 shots. Twice.....
    Last edited by zippy06; 01-02-2019 at 08:32 PM.

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