very elementary question

Discussion in 'The Ammo & Reloading Forum' started by cjh7819, May 24, 2009.

  1. cjh7819

    cjh7819 New Member

    Apr 12, 2009
    I am new to reloading and my reloading manual says that max case length for 30/06 casing is 2.494 inches but then says underneath it trim to length 2.484 inches. I have some once fired brass that is just in between these two lengths. Do I need to trim them or are they allright to reload. Is it just after they exceed 2.494 they need to be trimmed back to 2.484 or is it everytime?

    Thankyou in advance.
  2. 312shooter

    312shooter Well-Known Member

    Mar 17, 2008
    Las Vegas NV
    You will be fine until your cases exceed the length noted on the data. Trimming the cases everytime is an option if you choose, for consistency. However the number of times you reload the brass should be reduced if you are constantly trimming it. Some of our sensei's will be along soon to shed more light on this. Have fun!

  3. Crpdeth

    Crpdeth Well-Known Member

    Apr 23, 2002
    Location location
    Don't let them exceed 2.494, If you WANT to trim them back to 2.484 each time, you aren't hurting a thing... I like to trim my cases each time because I think I get better target results with all my brass being exactly the same.

  4. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    Here is how it is suppose to work:

    When the brass is new it will be at the "Trim-To " length after sizing. As the brass is used it will grow in length. When it reaches the "Max" case length it is time to trim it back to the Trim-to length.

    The difference in most every caliber I have seen is 0.010 inches. If you allow the cases to get longer than the Max case length they may get crimped by the chamber, which will hold the bullet in the case too long. That will increase the pressures to the extreme. If you trim the cases shorter than the Trim-To length you are minimizing the holding power of the case on the bullet and if you crimp the case to the bullet then the crimp may not be done correctly. The trick is trim to the Trim-To length, measure it with every shooting of the brass, and trim it again when the case length AFTER SIZING exceeds the Max case length. Trimming more often than that is a waste of time and effort, in my opinion and the opinion of every reloading manual I have read. But it hurts nothing to trim the cases after every shooting if done AFTER SIZING the case.

    Only trimming when the Max case length is exceeded is close enough even if you crimp the case mouths into crimp grooves. Remember the difference in those dimension is only 0.010 inches and nothing in rifle cases indexes off that dimension when the round is chambered.

    Last edited: May 25, 2009
  5. jdon72

    jdon72 Member

    Feb 3, 2009
    Good infor LD
  6. Popgunner

    Popgunner Active Member

    Dec 3, 2005
    Your brass should be between the max length & trim to length & all the same length to be able to crimp into the cannelure. Once fired brass is usually between those two figures & is fine to load if the lengths are the same. Different lengths will have your crimps giving you fits. Not all ammo needs to be crimped but those cases should still be uniform for even bullet pull.
  7. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    If crimping is desired you may be better served with the Lee factory Crimp Die. It is not as sensitive to the case lengths all being the same. It works by squeezing directly inward with a collet in the die. Exactly where that squeeze is at is not that important as long as it is all on the case neck. But still the overall case length has to fall between the Trim-To and Max case lengths AFTER SIZING. That's an 0.010 inch window, usually.

    Last edited: May 25, 2009
  8. GMFWoodchuck

    GMFWoodchuck New Member

    Oct 9, 2008
    Binghamton, NY
    I understand why the cartridges need to be trimmed, but suppose my gun happens to have a long throat, could I let them get longer accordingly?
  9. Lotsdragon

    Lotsdragon New Member

    Apr 5, 2009
    Potosi, Mo
    Listen to crp, No I wouldnt let them get longer even with a longer throat on my weapon. Like the rest have said I like them to be consistent, thats the key........
  10. Freebore

    Freebore Member

    Apr 18, 2009
    Land of the Free
    Longer throating should not have any affect on case length requirements, triming, etc. Throating is generally the distance between the cases actual chambering, and the engagement of the rifling (also known as "freebore").
Similar Threads
Forum Title Date
The Ammo & Reloading Forum Primer seater for everybody. Oct 8, 2016
The Ammo & Reloading Forum Reloading Manual Discovery? Feb 4, 2016
The Ammo & Reloading Forum This was an interesting discovery... Dec 7, 2014
The Ammo & Reloading Forum ...ever heard of weighing every completed pistol round? Nov 15, 2014
The Ammo & Reloading Forum Very interesting post on the effectiveness of .223/9mm rounds in combat Oct 10, 2014