how important is case length to accuracy?

Discussion in 'Reloading' started by dmax1800, Jul 18, 2013.

  1. dmax1800

    dmax1800 Well-Known Member

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    I have Norma brass for a 300 win mag. I probably have 8 to 10 firings thru the brass. I've used a chamber length guage and all the brass is way less than the chamber length. I've never trimmed the brass because it is way less than the chamber length. How important is it from an accuracy standpoint to have all the brass exactly the same length even though it is way less than the chamber length???
    Thanks.
     
  2. boomtube

    boomtube Well-Known Member

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    Not much.
     

  3. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    +1
    Similar length is most important as it helps create uniform neck tension
     
  4. MTBULLET

    MTBULLET Well-Known Member

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    if "not much" is your accuracy standard,
    then don't trim to uniform length.
    (or do any of the other brass prep steps)
     
  5. g0rd0

    g0rd0 Well-Known Member

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    that all depends on what you are doing with your rifle.
    If you are shooting gophers at 500 yards then the more consistant you are with your loading (trim length, powder charge, primer, case capacity seating depth, ect.) the more accurate you will be.
    On the other hand if you are shooting moose at 10 yards who needs accuracy?
    If you want extreme accuracy you must make extreme efforts, you only get out of it what you put into it
     
  6. boomtube

    boomtube Well-Known Member

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    "if "not much" is your accuracy standard,
    then don't trim to uniform length.
    (or do any of the other brass prep steps)"

    Then again, maybe it depends on our ability to discriminate between what's meaningful and what isn't. It seems new guys major on trivials, maybe because that's what they can wrap their minds around?

    Case prep can only go so far. Anyone thinking a zero tolerance for case length is a rational "accuracy standard" is gonna go nuts trying to figger out how to match primers in precise brissance batches or how to determine actual bullet grip from different cases vs. so-called "neck tension" and counting powder out by kernals. :D

    More reasonable folk use a bit of common sense and recognise that a few thou difference in case trim length is meaningless in the larger picture of fine accuracy from high capacity (long range) cartridges. Learn to properly develop an accurate load and most folk will be amazed at how tolerant it will be about the trivials new guys like to agonize over; like high precision case length. lightbulb
     
  7. varmintH8R

    varmintH8R Well-Known Member

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    WOW. Well said and so true. yet I'll still trim mine because I'm a hobbyist and I have reloading-related OCD.
     
  8. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    +1
    Many moons ago I had little access to reloading equipment and hardly had any time to do case prep and cleaning. My reloads looked like hell, I tossed charges, and I didn't trim until they were seriously over length, but I still managed to bag my deer every year, shoot prarie dogs with my savage pistol like they were going out of style, and put custom rifles to shame consistantly at the range with lowly factory rigs.
    I had set my pipes up with loads that simply didn't really need the case prep to stay well below moa. I'm sure I could have shaved a few thou. off a group here or there with prepped brass but it worked. I do now prep my brass to a point but I believe in the K.I.S.S. principal and won't do anything that is simply make work.
    Back when I lived with my parents my Pops was getting perturbed at my grousing on primers and powders so he had me do an experiment with my '06. We took a known 1/2 moa load with the rifle and loaded it with three brands of brass and three different primer brands. The resulting scrub ammo was still sub moa. I realize not all combos will do this and if you are to close to the top if could be somewhat dangerous, but you may want to get a bigger rifle if you really need to run red line all the time.
     
  9. dmax1800

    dmax1800 Well-Known Member

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    My Barnes reloading manual says the trim to length is 2.620". My fired brass measures from 2.606" to 2.653". Using a chamber length guage, my chamber is 2.661". The new brass from the same lot is 2.607" to 2.611". For the sake of consistency, do I trim all the fired brass back to 2.620" and throw out the brass that is less than this??? Or since it is all way less than the chamber length, just shoot it and not worry about it???
     
  10. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    What is your rifle telling you??? If it cares at all I'd trim to 2.606" and call it. I suspect you don't have to though and can trim to 2.620" and let the short brass "grow up" a bit.
    I don't throw an oddball brass away if it has a burr or partial crack in the mouth. I trim past it and shoot it until it grows up. I've had cracked necks and separated brass blow a group, but never one that is just a bit short. Yes it is better for uniformity to have uniform brass length, but how much is something the rifle has to tell you.
     
  11. boomtube

    boomtube Well-Known Member

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    "WOW. Well said and so true. yet I'll still trim mine because I'm a hobbyist and I have reloading-related OCD."

    So do I, within reason. Certainly case trimming is important for both safety and, potentially, accuracy but after a point the consistancy won't matter a bit. I know much of my picky case prep is to satisfy myself but I have no illusions I'd want to pass on to others that some of what I do is going to make any detectable difference for me or anyone else.

    Cases that are properly sized to match the chamber it's fired in will grow quite slowy. Those that get the shoulders set much too far back will stretch quite fast. For what it's worth, I trim to SAAMI length (within a thou or two more or less) and usually trim again after it exceeds about 5 thou, usually takes 3-5 hot load firings; I know my chamber lengths and that's quite safe FOR ME.

    Book "trim to" case length is always 10 thou less than max but that's only a common sense suggestion, it's NOT a specification to be adhered to or die.