How often to trim rifle brass ?

Discussion in 'The Ammo & Reloading Forum' started by thomas44, Sep 21, 2008.

  1. thomas44

    thomas44 New Member

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    Just wanted to get some feedback on how often you guys trim your rifle brass ? I was doing it every time, and started slacking off. I figured I'd trim and chamfer everything this winter when I'm deep into reloading every single piece of brass I own. I don't push the pressure envelope at all. I reload .223's, .22-250 and .243. Thanks !!
    I attatched a couple pictures of my Savage model 12 "Tiger Shark" .223.I love this rifle !!

    Attached Files:

    Last edited: Sep 21, 2008
  2. Popgunner

    Popgunner New Member

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    It all depends on what pressures you're running & how soft your brass is. The hotter your loads the more your cases lengthen. Just make sure to measure cases & stay under the maximum. You don't want the cases to be so long the mouth gets pinched onto the bullet & pressures jump. With mid-range loads you can get quite a few loads before trimming. In something like your .243 with fairly stout loads you should be getting about 5 loads before trimming. For safety, you can usually trim 4 times. When the cases are ready for their 5th trimming scrap them. The area you need to watch when your cases have been trimmed a couple of times is where the brass on the back end goes from thin to thick. This is where "incipient head separations" & later head separations occur.

    The load manual with the most info on trimming is "Complete Guide to Handloading" by Phillip Sharpe
    Last edited: Sep 22, 2008
  3. Bindernut

    Bindernut Well-Known Member

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    +1 on what pop posted. There isn't a hard-n-fast rule on when to trim, that'll depend on the brass you're using, how hot the load is, how tight your rifle chamber is, shape of the case, etc...

    Measure your brass after every resizing and once it hits the max length then plan on trimming it.
  4. LDBennett

    LDBennett Well-Known Member

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    How often to trim? ..... When your brass tells you its time!

    Gather your brass and take about five random samples cases from it. Size those cases in the normal manner. Measure the overall length of the cases. If any one exceeds the max length as listed in the reloading manual then trim the entire batch. Once they are all trimmed and as they are reloaded and used, it may take a couple of reloadings before the brass again tells you it needs to be trimmed. You can trim every time if you wish just don't trim the brass to shorter than the "Trim to" length listed in the manual.

    The window of acceptable case length is usually about 0.010 inches. If the brass is coming out of the gun in the window between Max case length and the "Trim to" length then trimming is not necessary. Trimming is only required when the Max case length is exceeded. More often trimming is just extra work.

    NEVER reload cases that are beyond the MAX case length. The extra length may hit the chamber wall in the worng place, wedging the bullet in the case at firing, and creating extra unsafe pressure in the gun.

    In summary, SIZE first, measure, then trim.


    LDBennett
    Last edited: Sep 22, 2008
  5. JLA

    JLA Well-Known Member

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    Lyman makes a case length guage. its a neat little piece of aluminum with various different lengths cut into the center of it. it will tell you when your brass is a little on the long side, and is made for nearly every commercially manufactured cartridge in america, and certainly covers the three you mentioned. i will usually load for my rifles in batches, and when i come around to re-loading, every piece gets passed through this handy gadget after the resizing process, every time. if i get even 1 of the 50 or a 100 pieces in the 'batch' that even so much as catches in the guage i will trim them all. It save bundles of time, and eleminates the 'chance' you take when you draw a random 5. I have seen what the pressure spike a long case affords the rifle and shooter, and lets just say the risk isnt worth the potential consequence. BTW, the shooter i mentioned is a good friend of mine and used to draw the random 5 until the rifle he was shooting bulged the barrel out just ahead of the chamber. The rifle just happened to be worth a penny or two being a custom built single shot in 7mmSTW, which is probably the hottest 7mm cartridge in existence. the barrel was a shilen hammer forged, button rifled barrel, cryo stress relieved, with an 11 degree facing, this rifle had about 3500 bucks invested before the 1100 dollar rebarrel, and he says he counts his blessings he wasnt shooting one of his old military bolt guns when it happened...
  6. thomas44

    thomas44 New Member

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    Thanks guys ! I appreciate the input.
  7. RustyFN

    RustyFN Member

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    I open my dial caliper to max case length and lock it. After I size a case I run it through the caliper. Anything that doesn't touch goes in the load bucket and the ones that touch go in the trim bucket.
    Rusty

    Edit: BTW nice looking rifle.
    Last edited: Oct 15, 2008
  8. getgot

    getgot New Member

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    measure twice....cut once
  9. Gene Seward

    Gene Seward Member

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    Once the case body reaches a length that is over max. isn't it time to toss it? I know that trimming the neck can shorten the OAL, but from the base to the neck is over max. there is nothing to do but toss. Right????
  10. Bindernut

    Bindernut Well-Known Member

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    That's what full-length resizing does for ya. When you resize, the shoulder will be formed back to near SAAMI specs for that cartridge. the extra brass will get swaged forward and into the neck...that's where the trimming comes in handy.
    If you're reloading for an auto-loader, you may need to go one step further and use a "small-base" sizing die which will also resize the lower part of the case even closer to it's original dimension.
    If the shoulder of the case isn't being set back far enough when you're resizing, then it's possible that either your rifle has a very tight chamber or your dies are too long or they're just not adjusted properly.

    One thing you do need to watch for is as the brass flows forward from repeated firings and resizings it will make the base of the case (right above the case head) thinner. After all, all that brass that you're trimming off has to come from somewhere right?
    Here's a page with a few pix. http://www.exteriorballistics.com/reloadbasics/caseinspect.cfm
    Google "case head separation" for more.

    With neck-sizing, you're not resizing the case back to SAMMI specs...rather you're leaving it fire-formed to your rifles chamber. You'll get less stretching in this situation.



    I typically see at least 6 or 7 full-length resizings in most of my rifle cartridges before I see signs of head separation or neck splits...have had some go much longer than that though too. A lot depends on how hot your loads are and how tight your rifles chamber is (loose chamber or excessive headspace). The more the brass can expand when it's fired, the faster it'll fatigue out.
    Last edited: Oct 15, 2008
  11. Gene Seward

    Gene Seward Member

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    Thanks Binder. That is the info. that I was needing.
  12. LDBennett

    LDBennett Well-Known Member

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    Originally Posted by Gene Seward:

    "Once the case body reaches a length that is over max. isn't it time to toss it?"

    NO!

    Everytime you shoot the cartridge and full length resize it, it may end up longer than the case overall length spec in the reloading manual. If it does not, then just reload it again. But if it does then you trim it, and only then. You trim to the trim-to length in the manual, usually 0.010 inches shorter than the max case overall length spec. You can get five to ten reloads out a case, depending, and you may only have to trim it every second or third time you reload it or maybe even less often. You make the measurement to decide to trim or not, AFTER full length resizing the case. I random select about five to ten cases out of a lot of fired cases and size them. If any one measures out of spec for case overall length I trim the entire lot.

    Note that magnum rifle belted cases get extremely less life (without special techniques) as do some lever action rimmed cartridges from some lever guns.

    Cases get thrown out when:

    1). The primer pockets get loose and you can feel that it doesn't take much force to seat the primers

    2). The case necks split or burn through..this is the common thing I see

    3). The case heads from a particular lot of cases start to seperate or show signs that they might seperate. One case head seperation from a lot means the lot should be tossed or at least be inspected. The thinning is just above the case head and can be felt with a bent probe in the case. See your reloading manual for details.

    All this means your cases should be seperated by purchase and use based on good record keeping data. Throwing all your brass in to a big bucket will lead to random case seperations and a bunch of cases whose life expectancy is unkown and for sure will fail at the least inopportune time. Digging the front part of a seperated case out of a rifle's chamber is not easy to do and may ruin your shooting day or your big hunt.You may also get gases from the seperated case back into your face.

    Gene. Go back to your reloading manual and re-read the section on trimming brass and case life. You are obviously confused.

    LDBennett
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