Explaining Headspace

Discussion in 'The Ammo & Reloading Forum' started by Insulation Tim, Jun 6, 2010.

  1. bluesea112

    bluesea112 Active Member

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    If the .45 acp is spaced on the mouth of the cartridge, then am I correct to think that crimping may allow the cartridge to slide too far foward without catching on the lip? I have been using a Lee factory crimp on my .45 acp, and I have not run into a problem. Now I am thouroughly confused, because what I just read tells me that I should be having a problem. What am I missing here?
  2. woolleyworm

    woolleyworm Active Member

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    A taper crimp is not anything like a roll crimp, I always like to think of a taper crimp as a " squeeze " to get to the final dimension, it really just removes the flare from the seating process more than anything.
  3. Alpo

    Alpo Well-Known Member

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    Bluesea, it really depends on the gun.

    I use the Lee Factory Crimp Die on my 45 ACPs. I have no problems with them in any of my 1911s. I can also shoot them without the moon clips in my 1917, 1937 and 625 Smith and Wesson revolvers. However, if I try to use them without the clips in my 1950 Smith and Wesson revolver, they fall past the step and will not fire. Firing them with the clips works, so I know the gun works. Using factory ammo without the clips works, so I know the step is there. But, my reloads will not work in THIS gun, without moon clips. The only thing I can come up with is that the chambers of THIS gun are at maximum size.
  4. bluesea112

    bluesea112 Active Member

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    Thanks for clearing that up guys. I forgot to mention that I am shooting the .45 acp's in a Sig P220.
  5. CampingJosh

    CampingJosh Well-Known Member

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    I had a fun experience in my local shop yesterday. A guy came in with three pieces of fired .223 brass. All three had the primers blown back just a bit, and one was split just about 1/4" in front of the head.
    He said that these were the first three rounds he had fired in his brand new Marlin rifle. The guy behind the counter just kept saying that the only thing that could cause that would be overcharged ammo. I asked him if he had reloaded it, and he hadn't. It was factory ammo from two different manufacturers (Remington and Winchester).
    I told him it was a headspace issue. Then the shop owner decided to call one of the guys he knew at Remington's service center in Illinois (shop owner used to be a sales rep for Remington). The phone call confirmed what I told him, and that rifle is going back to be rebarreled.
    Before I mentioned headspace, the guys at the shop had just about convinced the guy to go home and try firing it with some Federal ammo. :rolleyes: While I've now read a couple different reloading manuals, it was this thread that originally taught me about headspace. So our discussions on here are helpful to the safety even of shooters who've never heard of TFF. :)
  6. Innovative

    Innovative New Member

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    Headspace is the clearance in your chamber between your case head and the breech. It can be measured in several different ways, and there's a different story for each type of cartridge. Some of the most popular cartridges are rimmed, non-rimmed and belted. Here's a good article (I wrote it) that explains headspace.

    Understanding Headspace

    Headspace is different to someone that's installing a barrel, and special go/no-go gauges are needed. Chamber clearance (at the shoulder) is also important for shooters that want to make quality handloads. However, the handloader uses different tools to measure the chamber clearance that his loads have in his particular chamber.

    - Larry
  7. NEILT

    NEILT New Member

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    Thanks for explaining that
  8. Edward Horton

    Edward Horton New Member

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    [​IMG]
    [​IMG]


    And excess headspace. :eek:

    [​IMG]
  9. jack404

    jack404 Former Guest

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    100% correct

    all these fancy night clubs and such have way too much headspace ...
  10. madbuck22

    madbuck22 Member

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    this thread has been informative and entertaining. I give it an 11.
  11. CampingJosh

    CampingJosh Well-Known Member

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    Edward, that's a great graphic! Thanks for adding to the thread.
  12. Edward Horton

    Edward Horton New Member

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    For you Enfield collectors and shooters. ;)

    Its not the headspace that gets you, its actually the "HEAD CLEARANCE" or the air space between the bolt face and the rear of the case that causes your cases to stretch. This applies to any type case, rimmed, rimless, belted etc.

    [​IMG]

    [​IMG]

    Many people blame the Enfield rifle for short case life, the real problem is American commercial factory cases are not made to British military specifications. If any cartridge case is properly fire formed with the base of the case against the bolt face it will last much longer.
  13. madbuck22

    madbuck22 Member

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    this might be a stupid ? how do u get the original head space back from your fired round is it when u put it through the re sizing die? or when u trim?
  14. CampingJosh

    CampingJosh Well-Known Member

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    No stupid questions, madbuck. We were all new at some point, and for some of us (me in particular) it was more recent than others.

    Resizing a case will return it to the original exterior dimensions as though it had not been fired. This should cause the case to headspace correctly no matter how it does so (on the rim, the belt, the shoulder, etc.). However, if a case is too long, that case or a bullet seated into that case can cause problems with headspacing (among other possible issues).

    So really, you need to both size and trim (if over max length) to make sure that previously fired cartridges be safe to use again.

    Clear as mud yet? :D
  15. madbuck22

    madbuck22 Member

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  16. Edward Horton

    Edward Horton New Member

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    On a bolt action rifle you only need to push the shoulder back .001 to .002 when full length resizing.

    A full length resizing die is designed to push the shoulder back .002 shorter than minimum headspace. If your actual headspace is .003 more than minimum headspace and you die is set up to make hard contact with the shell holder you will be pushing the shoulder back .005 or more. This will cause case head separations and short case life and could als effect accuracy.

    Below simple ways to control and measure cartridge headspace.

    [​IMG]

    [​IMG]

    [​IMG]
  17. mw0248

    mw0248 New Member

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    you guys need a little coaching here;
    I'm talking about RIFLE rounds, but the same kinetic principle aplies to pistol, and revolver cartridges as well;
    When the bolt of your rifle is locked, there is a 'head space', that distance between the back end of your round, and the bolt; Usually around .001-.002 of an inch;
    When your round fires, the PRIMER actually moves back, and hits the bolt face;due to the round (the brass) expanding into the chamber dimensions of your rifle; a gas seal is formed when your brass expands into your chamber, and gess what? The only thing that can move is your PRIMER; and the bullet; The primer hits the bolt face, and sits there, waiting for the shell ( the brass) to decompress as the bullet goes down the barrel, and the PRIMER actually re-seats its self back into the spent shell;
    This is what headspace is about; Too little headspace can't be measured; simply because, if your round wont chamber, it's not a headspace problem; It's a chamber broblem;
    On the other hand, if you have a firearm that is shot out (neck/shoulder), this will allow
    the unfired round to travel too far forward, thus creating a "HEADSPACE" problem, cause it allows the PRIMER to go too far back, allowing gases to escape behind the back of the brass case that you are shooting; This causes all kinds of problems, some of which can cause injury/death if not taken care of;

    To an upcoming shooter, HEADSPACE can be confusing, but its just physics;

    If you shoot a lot like I do, then you find these things out;

    Lot easier now, than when we tried em out;

    By the way, I have a SUPER .243 load with 95 gr. if you are interested (bulls eye at 200 yds);
    Shoot well, and be safe!!
    Mike
  18. mw0248

    mw0248 New Member

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    when you 'full length' resize a shell, you stretch the shell FORWARD, cause thats the only way it can go; the brass thins as is it stretched and gets longer, causing it to get thin; then you get split cases, due to pressure more than the thin case can take; and you also end up trimming them for being too long;

    The above mostly applies to autoloaders;

    If you shoot a bolt action, or lever action rifle, dont full length re-size your cases;

    just collet size them for the neck size of the round you are shooting; you have a perfectly sized shell for your rifle; and your cases will last ten times longer;

    From LEE 2ND EDITION RELOADING MANUAL
  19. passagenight

    passagenight New Member

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    Ok, understood; I think...but I have a Marlin 1895 and a Ruger #1 both chambered for the 45/70. I reload, and have done so safely so far. These are rimmed cases of course which would define the headspace as being almost immaterial?.......but some rounds will chamber in the Marlin and will not chamber in the Ruger. The difference seems to be the 'taper' of the bullets used. If tapered the Ruger will chamber; if 'rounded' it hangs up just in front of the rim. Of course I don't force this.
    Is this a case where the bullet is engaging the rifleing of the barrel on it's curvature?
  20. howlnmad

    howlnmad Well-Known Member

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    It sure sounds like that's your problem. Are you seeing marks from the rifling on the round nose bullets?
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