More important - OAL or weight of brass

treedoc

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What's more important for precision loads, grouping all brass by weight within + or minus 2 grains or OAL within how many thousandths? Or maybe a combination of both. Inquiring minds want to know.
 

ChrisGarrett

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Re: More important - OAL or weight of brass

OAL, especially if you're shooting VLDs.

Brass weight and bullet weight, will show up mostly at longer ranges in vertical stringing, as you'll be getting inconsistent (relatively speaking) velocities.

Still, if you run the standard deviations, you won't see minor variances show up say under 500 yards?

Getting that bullet to travel down the bore, in a straight and true manner, is pretty important.

Garbage in, garbage out.

Chris
 

treedoc

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Re: More important - OAL or weight of brass

Chris:

For example, if I have 100 pieces of .308 brass - lengths 2.010-2.015; would you have 5 groups to the .001 or 2 groups to the .002?
 

BCP

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    Re: More important - OAL or weight of brass

    I loaded up 100 LC mixed brass 43.5 varget 168 nosler this past week where 50 were all same headstamp and very consistent overall and the other 50 were mixed LC headstamp and OAL that varied by 1.995 to around 2.005 at the most for the brass, and OAL went from 2.8 to 2.805. Both batches grouped 1.5" at 200. I don't think it matters that much if you're just plinking or shooting at steel but I imagine that if there are differences they will show up at longer ranges.
     

    MitchAlsup

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    Re: More important - OAL or weight of brass

    In my opinion, the order of relevances:

    A) The quality of the bullet being shot
    B) The tune of the recipie to the gun
    C) The precision and accuracy of the charge weight
    D) The meticulousness of the reloading process

    Now, also in my opinion, once you have all of the above tuned up so that you gun is delivering 0.5 MoA on average with a significant number of 0.3" 5-shot groups, then some other stuff starts to mater:

    F) Sizing die setup
    G) Neck tension
    H) Brass preperations
    I) Case weight

    I've left out powder choice, primer choice, and jump distance; as these should be covered up in B above. Meplat trimming or pointing is covered under A above.
     

    ChrisGarrett

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    Re: More important - OAL or weight of brass

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: treedoc</div><div class="ubbcode-body">Chris:

    For example, if I have 100 pieces of .308 brass - lengths 2.010-2.015; would you have 5 groups to the .001 or 2 groups to the .002? </div></div>

    I like Mitch's ranking just above.

    I'm not to anal any longer about brass length and if I'm within .005" from the low to the high, I'm not worrying about it too much.

    If you've taken the time to measure and segregate that brass into groups of 2.010", 2.011", 2.012", 2.013", 2.014" and 2.015", you might want to place them in order, into your two 50ct boxes and shoot short to long, but you'll no doubt have odd numbers.

    This is the problem with weight sorting and bullet OAL sorting, you'll need a larger sample size to get the batch amounts you plan to shoot. You'll never get things dead even and you'll have stragglers to deal with which will drive you nuts.

    If you had them all trimmed to 2.010", you could then weight sort them, but for anything less than competition shooting, I don't think differences of +/- .0025" is going to matter too much.

    Find a bullet/powder/primer combo that gets you decent groups, then fiddle with COAL/OAL seating depths and tune it further. Prep your brass and trim it uniformly, if you want to go 'full retard' and then worry about practicing your aim.

    We all have limited 'free time' and one has to pick and choose his targets. Ideally, it's all exactly the same from one cartridge to the next, but this requires a lot of time to realize.

    Chris
     

    Fuzzball

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    Re: More important - OAL or weight of brass

    "or OAL within how many thousandths? Or maybe a combination of both. Inquiring minds want to know."

    Goodness. Perhaps case volume is the important factor?

    OAL refers to the length of a cartridge (ie, Over All Length), not case length.
     

    treedoc

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    Re: More important - OAL or weight of brass

    Thanks for all the information guys.

    Fuzzball - you're right, too much PBR at lunch caused some confusion with OAL and case length. Next time, I'll drink a couple more before I post, lord knows what I may ask then.
     

    ChrisGarrett

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    Re: More important - OAL or weight of brass

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">"or OAL within how many thousandths? Or maybe a combination of both. Inquiring minds want to know."

    Goodness. Perhaps case volume is the important factor?

    OAL refers to the length of a cartridge (ie, Over All Length), not case length. </div></div>

    Actually, COAL refers to the distance between the bullet's tip and the case head face. OAL is the arbitrary measurement from the bullet's ogive to the case head face. Arbitrary because the hole in the gage one is using, isn't a standard diameter.

    Chris
     

    Fuzzball

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    Re: More important - OAL or weight of brass

    COAL (cartridge over all length) and the simplified OAL (over all length) are interchangeable terms. Neither applies to head-to-ogive length. For my own notes I use HOL for head-to-ogive lenght because I've never seen anyone come up with a popularly accepted term for that measurement.

    Commercial ogive measuring tools may vary in diameter but, if they are made corrrectly, they will be very close to proper bore diameter for the caliber. My two are but I haven't measured everything on the market.

    Treedoc, my comment wasn't meant as a put-down but we do have a technical activity. If we let our terms get away from us other people will pick it up and we'll soon lose the ability to ask or answer anything for certain!
    wink.gif
     

    treedoc

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    Re: More important - OAL or weight of brass

    10-4 Fuzzball, no offense taken. Thanks for the info.