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Is sizing brand new brass Necessary?

Discussion in '10mm Reloading Forum' started by orangeride, Jan 12, 2013.

  1. orangeride


    Oct 19, 2011
    I'm getting ready to load some 165gd in new stairline brass. Is it Necessary to size it?
  2. TDC20


    Apr 11, 2011
    Necessary depends. Unless the brass has been really beat up in shipping so the mouths are out of round, then no, it's really not necessary. If you're loading up something that you shoot all the time, like something a little backed off from a max load so you can throw unweighed charges, and you are familiar with the load's performance. However, if you are going to do load work-ups and chrony loads, you should definitely spend the time to resize. Resizing your brass is going to do two things. First, it's going to give you a much better baseline for neck tension on the bullet, which will then match your reloads in the same brass. It may also adjust the case volume a slight bit, which is probably not going to matter much, but it is another variable you can control. Any variables that you can control and remove from affecting your load data, if you're concerned about collecting the best data (i.e., you're weighing charges and using a chrony), then definitely resize your new brass. But if you're loading up something you're already familiar with (not a redline max load) where you're going to throw unweighed charges and you're in a hurry, then you can probably skip it.

    I resize all my new brass anyway, because it only requires about 10 minutes per hundred since I use carbide dies and no lube. It's really not that much of an inconvenience to get the added neck tension consistency. And since I weigh all my full-power charges, that consistency is important to me.

  3. MinervaDoe


    Jan 26, 2009
    San Jose, CA
    .... but, I have a progressive press, so I just run it all through all the dies.

    But even when I used a single stage press, I'd resize new brass at the same time I primed it.
    Last edited: Jan 12, 2013
  4. _The_Shadow

    _The_Shadow Ret. Fireman

    Jul 23, 2007
    Southeast, LoUiSiAna
    There are those that say the case mouth should be debured as this helps especially on progressives press for smoother operations of some steps...
  5. Taterhead

    Taterhead Counting Beans

    Dec 13, 2008
    Boise, Idaho
    I resize new brass partially down to cover at least the part that grips the bullet. Most likely not a safety issue to skip this step, but re-sizing will give uniformity and fix any brass that got out of round while in shipping. I neck size new rifle brass.
  6. ModGlock17


    Dec 18, 2010
    I've probably the lowest years in reloading experience around here... Just got a Lee Loadmaster, a progressive press, and figured out a way to skip sizing on new brass. Sizing puts scratches on brass. Case mouths are enlarged with powder drop stage so that is uniformly done. I just like ammo with brasses that have no scratch on them... Makes me look like a pro. LOL.

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  7. rdm1962


    Dec 22, 2012
    St. Charles MO
    I have been reloading for 25+ years. I currently load for and shoot 30 different calibers. On more than one occasion I had a failure to feed situation when I didn't re-size new brass. My hand gun, 5.56, 308 and 30-06 all get run through my Dillon 550. All the calibers that get shot in volume or in a semi. I will single stage all other rifle rounds.

    When you set up your progressive press, you install a sizing die. Why not use it? Consistency in the assembling of a load is just as important as the development of that load. IMO if you skip a step sometimes, can you be consistent? Re-sizing is just step the operation. How ever if you have a fail to feed at a critical time is that second or 2 of time you save worth what might be lost, ie. point at a match, trophy game or in a defensive situation? I say size your new brass. Ralph
  8. ModGlock17


    Dec 18, 2010
    Rifle brass is different. Working with them is like a jewel operation. Accuracy is of prime importance and brass needs to be fire formed to a specific barrel chamber to achieve top accuracy. I Never use new brass if I want accuracy. This means the first firing of new brass is just for fun, for me. New rifle brass tend to be deformed at the neck on shipping and handling, so resize is necessary.

    Specifically for Starline 10mm, I haven't seen a deformed brass as yet. The 10mm will never have the accuracy of a rifle round, just the nature of handguns. For me, smooth feeding is of prime importance in 10mm. I also recall the late Mike Willard of SwarmFox skipped resizing new brass. Take a look at commercial rounds for 10mm, see if you can find scratches on new brass.

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  9. dm1906

    dm1906 Retired SO

    Sep 7, 2010
    PRK (Kalifornia)
    If your sizing die is "scratching" your brass, you need to replace that die. No die should scratch the brass. Call Lee and they'll replace it. I size all new brass, rifle or pistol, and have none scratched, with one exception. I've been using a Lee carbide .45ACP die set for about 30 years, and just recently retired it. It scratched a case. Not bad for 150K+ rounds. I've retired Redding and RCBS dies with less than 1/4 that use in other calibers, all carbide.
  10. nickE10mm

    nickE10mm F.S.F.O.S.

    Apr 13, 2004
    Wichita, KS
    Yes, I personally always resize new brass. My DIE is the correct dimensions and I would prefer that my brass be perfect. Yes, it DOES show that the brass has been touched but I'd prefer slight, slight markings to something that may or may not function correctly. YMMV.