.338LM Beginner Load Data

THN338

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May 25, 2022
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California
I've been reloading with my dad for a long time but finally just got my own setup ready for my new .338LM, and am looking for some advice or others' experiences with the cartridge. I have not developed my own loads before, my other rifles have been hand-me-downs with pre-existing load data from family who are experienced with those cartridges. My bullet and powder options are limited given ongoing supply chain issues and where I live (CA).

My setup:
.338LM Christensen Mesa Long Range w/Athlon Argos BTR 6-24x50mm
Barrel length: 27"
Barrel twist: 1:9.3
Bullets: 285gr Hornady ELD
Powder: Retumbo
Case: Factory new Lapua brass
Primers: Winchester large magnum rifle

Equipment:
Mostly older hand-me-down RCBS stuff, but I bought brand new micrometer adjustable dies for .338LM.
I already have a single press, powder measure, scale, deburring tool, trimmer kit, calipers, tumbler, etc.
 

DIBBS

Old Mountain Man-Tired occasionally Grumpy SOB
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  • Aug 21, 2008
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    Get a good loading manual or three. Data below has been developed for the particular firearm. Start low and work up. H1000 and VV-N-570 have worked well for me. I use CCI 250's or FED 215's, not sure how the Winchester primers will work out for you.

    Let your rifle tell you what combination she likes.


     
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    spife7980

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    Feb 10, 2017
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    Your powder manufacture will have the online data that I trust most

    1653499892628.png
     

    powerspc

    Based on Results
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    Mar 15, 2018
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    From the Hornady Manual (11th Edition) for 285gr ELD:

    Start: 81.7
    Max: 93.0


    Powder: Retumbo
    Case: Hornady
    Primer: Fed 215
    Max COL: 3.681"
    Barrel: 27.17", 1:10 Twist

    Start low and work up!
     

    THN338

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    May 25, 2022
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    California
    From the Hornady Manual (11th Edition) for 285gr ELD:

    Start: 81.7
    Max: 93.0


    Powder: Retumbo
    Case: Hornady
    Primer: Fed 215
    Max COL: 3.681"
    Barrel: 27.17", 1:10 Twist

    Start low and work up!
    That's perfect, it's almost exactly in line with my dimensions. Thank you!
     

    Lazyninja

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    Dec 20, 2020
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    I have the christensen mpr in .338LM my rifle has an obnoxiously tight throat form the factory which seriously limits the ability to seat the bullets out and robs case capacity. Also causes pressure often under book maxes.
    !I feel it's imperative with christensen rifles to have a coal gage and test every bullet you plan to use to determine your max seating length! Obviously it's a good practice in general but there is too much variation in clambering with christensen to risk it.
    Below L-R .280ai, my load lapua brass berger 300, berger factory same components
     

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    powerspc

    Based on Results
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    Mar 15, 2018
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    Its got 275 and 300 which are close enough. Interpolate.
    To the OP, I happened to have the Hornady data but just an FYI since you’re new; ^ this guy knows his shit inside out and backwards and forwards. When you’re in between on bullet weight with published data you can interpolate as he said; and Retumbo is an excellent powder for .338LM.
     

    towerofpower93

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    OP, here's my last trip out with an MPA build that was throated for the 250gr SMK, meaning it's got a pretty short throat and I have to seat deeper than I'd like. While I'm over max, I started at 89gr and worked up in 1 grain increments until I got to 94.0, then went up in half grain increments to 97.0gr. No pressure signs, but I backed it off a grain as it was a little better ES/SD and the velocity had leveled out, so why burn an extra gain of unicorn dust for no gain...

    Dec 2019
    MPA 338LM w Titan-Ti
    Win LRM
    Retumbo 96.0gr
    2xfired Lapua
    Headspace: 2.270”
    Hornady 285gr ELD-M lot #2181455
    CBTO: 2.740”
    OAL: 3.600”

    11rds chrono’d

    LabRadar series: 153

    Lo: 2880
    Hi: 2908
    Avg: 2892
    ES: 28
    SD: 8.0

    And when I confirmed the load 5 months earlier

    July 2019
    MPA 338LM w Titan-Ti
    Win LRM
    Retumbo 96.0gr
    1xfired Lapua
    Hornady 285gr ELD-M lot #2181455
    CBTO: 2.740”
    OAL: 3.600”

    9rd group

    LabRadar series: 134

    Lo: 2850
    Hi: 2863
    Avg: 2859
    ES: 14
    SD: 4.2

    Guessing sitting loaded for 5 months did a little cold welding to the bullet/case mouth, or Retumbo did a thing and sped up in the cold.
     
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    White Mamba

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    Mar 28, 2011
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    H1000 with 91.8g or 92g , Lapua brass and 215m , 285 eld.
    You need to ladder up some loads for pressure but this is a typical accuracy load for 338s at around 2800fps
     
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