What length do you trim your .308 brass?

Leaddog

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I've been reloading .308 for quite a few years and have always trimmed my brass to 2.007. SAAMI spec is a maximum of 2.012.

What do you do and what is recommended?
 

BCP

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    Re: What length do you trim your .308 brass?

    If I have to trim I trim to 2.005. Only brass i have that seems to grow is federal everything else stays the same size.
     

    Victor N TN

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    Re: What length do you trim your .308 brass?

    For bolt action rifles I keep that brass seperate and trim to the chamber max as measured, -.005" to .010". My favorite 308 gets trimmed to 2.035"

    For gas guns I trim to the book.

    Measuring to the maximum length for "that chamber" keeps from burning the chamber throat as fast as trimming short. Different chambering reamers make the case mouth cut ditterent lengths.
     

    KYpatriot

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    Re: What length do you trim your .308 brass?

    I did what Victor said and came up with similar results for my Rem 5r, it has a long chamber (reamer must have been new :/) although I still trim to 2.010 just so all the brass is the same since they were different after firing a few times by a few thousandths. I don't know if having all the brass the exact same length is more accuracy producing than having a longer neck for more consistent tension.
     

    Lburt

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    Re: What length do you trim your .308 brass?

    My reamer is cut .010 longer than standard because that is what Dave Kiff suggested. I believe, but wouldn't swear to it, that it has something to do with once fired military brass that has been crimped and is now a little longer. Typicially, I trim new brass to 2010 and it usually wears out before it needs to be trimmed again.
     

    Victor N TN

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    Re: What length do you trim your .308 brass?

    Keeping the brass trimmed close to the chamber max will help keep the gasses from eroding the chamber throat as quickly. The shorter the brass is trimmed the fewer rounds it will take to eat out the throat.
     

    Leaddog

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    Re: What length do you trim your .308 brass?

    Thanks to all for your replies. I think my 2.007 will be just fine.

    As a side to the poster that mentioned throat erosion, I really don't see a problem with cases that are a bit smaller in a .308 running velocities in the mid 2600's. If I was running a Palma rifle at 2900fps+, then yes, maybe I'd go a bit longer.
     

    longebow

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    Re: What length do you trim your .308 brass?

    +1 on the Sinclair chamber length gauge. I then trim 0.010 short of that, and spot check the cases for growth. Leaving the cases longer seems to prevent them from growing as rapidly--it is probably due to a better fit between brass and chamber. You would be surprised to see the differences in chamber dimensions between different guns!
     

    armymedic.2

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    Re: What length do you trim your .308 brass?

    2.009, and isn't the max length 2.015? thats what is in the lee manual.....i don't touch them unless they are over 2.012
     

    Short-bus

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    Re: What length do you trim your .308 brass?

    2.005, however i've had it as short as 1.998 (electric trimmer setup for another shooter, didn't measure 'till it was too late) and still never had problems. I usually don't trim until they're upwards of 2.015".

    Branden
     

    GRIM

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    Re: What length do you trim your .308 brass?

    2.005 - heck some of the Winchester brass barely makes it to that length when it's new.
     

    FreshKills

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    Re: What length do you trim your .308 brass?

    I get this query a lot.

    Assuming a shred of sense,actual trim length is moot,but consistency isn't. So rather than getting hung up on a given dimension of 2.0xx",instead focus that all in the lot are the SAME length. That is where great results lay.