Case trim length

Discussion in 'Reloading' started by Pheroze, Mar 22, 2016.

  1. Pheroze

    Pheroze AH ENABLER BRONZE SUPPORTER AH Legend

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    I have been habitually trimming to the trim to length. But, I am thinking that keeping the case closer or at the maximum length will provide more grip on the bullet. Let's say about 0.050 from max. I have a couple of questions I hope someone can help me with:

    Is my thought on a longer neck giving a better grip a reasonable thing to keep in mind when prepping the cases (closer to the max length is better)?

    For decent hunting accuracy (around the 1" range) does it matter if the cases are not all uniform but within +- 0.050 (e.g. 375 H&H kept somewhere between 3.845 and 3.850). I am trying to figure out how diligent I need to be with a uniform trim length.

    Thanks
     

  2. Royal27

    Royal27 AH ENABLER AH Ambassador

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  3. Shootist43

    Shootist43 AH ENABLER GOLD SUPPORTER AH Legend

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    All of my reloading manuals show a max. case length of 2.850", with a "trim to" length of 2.840". My manuals all state that this cartridge needs to be "crimped" to prevent bullet movement. That being said, one needs to think about how case length differences effect the crimp. If your die is set to crimp a case that is 2.850" in length will result in very little to no crimp if the case is only 2.840" long. Personally I resize all the brass I intend to reload and then measure each one separately. I do about 10 rounds to see if I can attain a group of 5 that are the same length. Assuming those 5 are over the "trim to" length I accept a variance of .001" plus or minus and call it good. I then sort the remaining brass into 3 "lots", i.e. short, acceptable and long. I then trim the long brass to the middle of the "acceptable" lot. I can then reload my uniformed brass several times without re-trimming it. To me reloading is fun. I don't mind the extra work especially when it reduces my group size.

    I really think you incorrectly stated the maximum case length and that you slipped a decimal in your overall range. A difference of .050" is HUGE while a difference of .005" might be tolerable.
     

  4. PHOENIX PHIL

    PHOENIX PHIL AH ENABLER AH Ambassador

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    Yep trimming 0.05" below max seems extreme. I never go more than 0.02" below maximum. FWIW, I've never seen any measurable difference in accuracy in regards to the case length.
     
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  5. Pheroze

    Pheroze AH ENABLER BRONZE SUPPORTER AH Legend

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    Oops. You are absolutely right about the decimal. Sorry about that!
     

  6. Pheroze

    Pheroze AH ENABLER BRONZE SUPPORTER AH Legend

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    I don't trim beyond the trim to length intentionally. I screwed up the decimal in my post. Ugh. But, thanks for the insight on accuracy, that's what I was wondering. Assuming one stays within the recommended range, I was wondering if there is any variation in accuracy.
     

  7. PHOENIX PHIL

    PHOENIX PHIL AH ENABLER AH Ambassador

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    I ran a mini experiment where with a known accurate load, I loaded several rounds with very closely matching brass length and some several with varying brass length. Could not see a difference in accuracy between the two sets.

    The only advantage I've seen on having matching brass length is if you're crimping into a cannelure or a groove such as on a TSX. Depending on the OAL of your round, you could end up "above or below" the intended crimp point.
     

  8. Pheroze

    Pheroze AH ENABLER BRONZE SUPPORTER AH Legend

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    Thanks, that is very helpful. I have been spending an inordinate amount of time trimming up these cases!
     

  9. Desert Dog

    Desert Dog AH Veteran

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    Me neither. Neck tension is 100 times more important than case length in regards to accuracy.

    Some people just overwork brass. I trim down after the first firing, then am usually good to go for a few firings after that without trimming (depending on the caliber). Some sizing dies in certain calibers really stretch necks.
     
    Last edited: Mar 31, 2016
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