Bullet seating versus crimping...

Discussion in 'The Ammo & Reloading Forum' started by 1911Man, Jan 28, 2010.

  1. 1911Man

    1911Man New Member

    Jan 23, 2010
    St. Louis
    I'm still in the reading/researching/asking stage of reloading. I will be reloading .45ACP and am wondering what "crimping" is. Then, what is "roll crimping" and what calibers is that for? Do I have to "crimp" .45ACP? Is "crimping" different than what my bullet seating die does? Please outline, in detail, the scope of "crimping," "bullet seating," and whatever else about these I need to know.

    Thanks a bunch, folks.
  2. carver

    carver Moderator Supporting Member

    If you are reading your reloading manual this is covered in it. Sometimes ya need a crimp! Sometimes ya don't! All most anything you can think of will be covered in your reloading manual. Read it, then read it again, it ain't that much to learn.

  3. army mp

    army mp Member

    Jan 30, 2009
    western Pa,
    Crimping is done with your seating die. And yes I would put a crimp on 45ACP rounds. What most guys do is. Put a case in the shell holder. Move the ram to the top. Now back off the seater stem. Screw the die in till it comes in contact with the casing. Now you can start a bullet into the case and adjust. OAL.( over All length ) once you have proper. OAL Back the seater stem out about a turn . Now screw the die in about a ¼ to ½ turn. This should crimp the bullet. Check your OAL again. If correct, screw the seater stem down on the round in your press and you should be ready to load.
  4. techoca

    techoca New Member

    Nov 3, 2008
    The .45ACP uses a taper crimp; you need to make sure your die has a taper crimp and not a roll crimp. It probably does, but make sure. I seat my bullets with no crimp being done by the seating die (read the die instructions), then I taper crimp as a separate process using a Redding taper crimp die for .45ACP. Most of your hardcore .45ACP shooters or shooters with match barrels will do it this way. Many will argue that this is not necessary and it may not be for their uses, it is for mine.

    I will warn you of a potential problem if you use Lee Carbide dies for .45ACP. The Lee die only sizes the case to 1/8" from the bottom of the case, leaving the case too fat on the bottom and this will cause failure to return to battery issues on some guns with match grade or tightly toleranced barrels. Ask me how I know.:rolleyes:

  5. 1911Man

    1911Man New Member

    Jan 23, 2010
    St. Louis
    I've purchased RCBS carbides. I should be good, eh?
  6. techoca

    techoca New Member

    Nov 3, 2008
    Excellent choice 1911Man.

    Good luck with your .45ACP reloading, it is my favorite handgun cartridge to shoot and hand load. I load 200gr. Dardas LSWC over 5.0gr. Red Dot powder for range ammo and it shoots beautifully out of a 1911, very accurate load.
  7. army mp

    army mp Member

    Jan 30, 2009
    western Pa,
    Yes and if new Dies there should be directions with the Dies. But if you read your reloading Manual and ask lots of questions and be safe. You will be loading Ammo in no time.
  8. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    Here is the way the process works for pistol cartridges:

    The sizing die sizes the entire case down to a dimension that assures normal size bullets are an interference fit into the case (by a couple of thousands of an inch).

    The belling die bells the mouth of the case so that the bullet will just barely start into the case about 1/16 inch of so.

    The seating die pushes the bullet into the case to the right depth. The fit in most pistol cartridges can be so tight that the imprint of the base of the bullet can be seen through the case wall. This lets the bell, put on the case by the belling die, stand out from the case body and the cartridge MAY not fit into the chamber of the gun so there must be a process to push the bell back into the case.

    The body of the seating die can be adjusted to remove the bell or to crimp the case throat into the bullet. That allows the bell to be removed and the bullet to be semi locked into the case.

    If it is an auto-loading cartridge like 9mm, 10mm, 40 S&W, or 45ACP (there are others too) the crimp is a taper profile. If it is a revolver cartridge the crimp is a rolled over edge usually into a grove or cannelure in the bullet body. Never uses a roll crimp on a cartridge that head spaces on the mouth of the case (like virtually all semi-auto calibers... see list above).

    When any crimp is applied it is important that the diameter of the cartridge at the crimp not exceed the dimensions given in the reloading manuals.

    Last edited: Jan 29, 2010
  9. mikld

    mikld Well-Known Member

    Jun 24, 2009
    No offence intended...

    But, first and foremost; you need a copy of ABCs of Reloading, or Lyman's 49th Edition Reloading Manual, or Lee Modern Reloading. Then get the other two. All the info you need to get started is in these three manuals. Read them and with that info you'll be able to buy the reloading equipment suited to your reloading needs. You'll get a lot of good info here too, but with a good manual (not just a recipe book) you'll have the info at hand in front of you. I been stuffin' brass for 35 yrs. off and on (lots of off) and still keep my manuals handy.
    Last edited: Jan 28, 2010
  10. 312shooter

    312shooter Well-Known Member

    Mar 17, 2008
    Las Vegas NV

    +1, Lymans 49th is a great read if you are into shooting, I guarentee you will be excited and well informed after this manual.
  11. bluesea112

    bluesea112 Active Member

    Nov 20, 2005
    West, TX
    The term "crimping" means pushing the mouth of the case in tight around the bullet after the bullet is seated in the case. Roll crimping actually rolls the edge of the case inward so that the edge of the case "bites" into the bullet. Taper crimping tightens the case against the bullet, but it does not bite into the bullet.
    From my experience, roll crimping increases pressure more than taper crimping when the cartridge is fired.
    Lee factory crimp is a type of taper crimping, and it is my favorite.
    I don't like roll crimping, because it is too easy to bulge the cartridge case (in my opinion)
    Last edited: Jan 29, 2010
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