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9mm COL

Discussion in 'Handloading and Reloading' started by gutterman, Feb 18, 2013.

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  1. gutterman

    gutterman Member

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    Can anyone tell me what the COL for the 9mm would be using a 124 Hornady XTP and 4.2 grns of Titegroup?
     
  2. rcmodel

    rcmodel Member in memoriam

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    No.
    There is no simple answer to that.

    You need to take the barrel out of your gun and use it as a gage to set OAL so it don't hit the rifling leade in the chamber.

    All brands of guns are different.

    Hornady manual suggests 1.060" is a starting point.
    But you still need to make sure it is OK in your barrels chamber.

    rc
     
  3. ATLDave

    ATLDave Member

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    Or he could get a case gauge and be assured that it will fit any SAAMI-spec chamber and barrel, right?
     
  4. Lj1941

    Lj1941 Member

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    Col/9mm

    I concure on using the barrel as a guage.I use the barrel of my M&P and never have any problems.
     
  5. Walkalong

    Walkalong Moderator

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    No, the gauge checks headspace and OD, but not anything else. Someone should come along soon and give us a definitive answer on what OAL the 124 XTP is loaded at by the factory.
     
  6. mike.h

    mike.h Member

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    in Hornady 8th, 124gr HP-XTP - c.o.l. : 1.060". However titegroup is not listed in the powders.
     
  7. ATLDave

    ATLDave Member

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  8. Walkalong

    Walkalong Moderator

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    Yes, forgot to type that, but it doesn't mean that that bullet combo at that OAL will chamber. The answer is still no, just because it is under or at SAMMI max OAL doesn't mean it will chamber in all guns.

    [​IMG]
     
  9. rcmodel

    rcmodel Member in memoriam

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  10. CZ9shooter

    CZ9shooter Member

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    The case gauge does not have any rifling to potentially interfere with the round completely chambering. An actual chamber of a pistol does. A full wad cutter seated to 1.169 (max) would probably fit the gauge, but definatley will not chamber in a 9mm firearm.
     
  11. beatledog7

    beatledog7 Member

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    Many "spec" reload OALs that chamber in my 9mm case gauge will not chamber in my CZs. Do the barrel test as rc recommends; if you've never done it, you probably need to clean the gun anyway, and this will be a good chance.
     
  12. Walkalong

    Walkalong Moderator

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  13. ATLDave

    ATLDave Member

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    I'm not about to disagree with the many august and learned members who say that cartridge gauges don't test bullet engagement with a barrel, so the following is truly a question, not a quarrel:

    I took one of my LE Wilson gauges and dropped a bullet - not a cartridge, just the lump of copper and lead - into it. It did not come out the other side. Does this not indicate that the narrowing of the gauge forward of the cartridge area is sized down to some SAAMI spec? Does SAAMI not specify dimensions for barrel throats?

    Again, these questions are not rhetorical. I don't know the answer and am eager to learn.
     
  14. rcmodel

    rcmodel Member in memoriam

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    Yes, SAAMI has chamber specs & ammo specs.
    But they are voluntary standards a U.S. manufacture can use, or not.

    But the CZ the OP ask about, as well as German SIG P6's and other foreign made guns do not adhere to U.S. voluntary standards from SAAMI.

    The European standards are set by C.I.P., and they are not the same as SAAMI.

    rc
     
  15. ATLDave

    ATLDave Member

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    Ah-ha! Now I get it. Thanks, as ever, for the wisdom, rc'.
     
  16. cja245

    cja245 Member

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    you can do a couple things, but as others said, case gauges are not for determining COAL, they are for max case dimensions including max COAL. You will almost never be using max COAL except maybe in a revolver.

    Your best bet is to use the barrel (removed from the gun) as a gauge. you want to seat till the case is fully chambered and the bullet is just touching the rifling. Then back off just a bit. This will usually give you the best accuracy.

    Also you can compare it to a factory FMJ round. When comparing side to side, seat the XTP so it is fully inside the ogive of the FMJ. This generally will give you the most reliability.

    Somewhere in between the measurements from these two methods is generally where I end up for best reliability and accuracy.
     
    Last edited: Feb 20, 2013
  17. bds
    • Contributing Member

    bds Member

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    +1 Although using the case gauge to check the outer dimensions of your finished rounds is a good idea to ensure they will work in ALL barrels, I prefer to custom tailor my rounds for my barrels so they produce optimal accuracy. Using the longest OAL that will reliably feed/chamber in your pistol/barrel/magazine will minimize high pressure gas leakage to produce more consistent chamber pressures which will result in enhanced accuracy. ;)

    Your Max/working OALs will be based on your barrel's leade/freebore lengths and the start of rifling (Use the barrel drop test to determine the Max OAL and function check to identify the working OAL).

    [​IMG]
     

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  18. Otto

    Otto Member

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    The barrel plunk test tells you nothing about rim diameter, thickness or damage.
    It can also fail to detect Glocked brass that aligns with the unsupported part of the chamber.
    I use the barrel for determining OAL but the Wilson gage is used for all other aspects of the loaded round ie. bullet diameter, body diameter and length.
    If my round won't fit the Wilson gage, it gets rejected.
     
  19. gamestalker

    gamestalker member

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    Every gun has it's own OAL needs. But Hornady does publish the OAL they tested it at, but there is no promise that the OAL they used will function properly in your firearm. My recommendation is to learn and then practice using your barrel for determining OAL.

    The OAL Hornady tested it at was 1.060" from a S&W M-39, 4" barrel 1-10 twist. Who knows how that will function in your chamber though?

    Hornady doesn't show Tite Group in there data. Sierra does for there 125 gr. Jacketed bullets 3.7 - 4.4 grs.. Speer also does for there 124 gr. jacketed 4.0 - 4.4 grs..

    GS
     
  20. bds
    • Contributing Member

    bds Member

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    After you determine the OAL that will work with your pistol/barrel/magazine, I would follow the lower load data for JHP bullets and work up from 3.8 gr instead of starting out at 4.2 gr.

    Hodgdon load data
    Lyman #49
     
  21. ATLDave

    ATLDave Member

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    As long as we're on the subject, I don't suppose anyone has a good formula or method for figuring out what a reduction of OAL by X does to pressure/max loads? IOW, if a published load shows 1.2600 OAL and I want/need to make it 1.2500, is there a predictable way to anticipate what pressure change would result and/or what reduction in charge is needed to hold pressure constant?

    (My current understanding is that the answer is "no, not really," but since rc' and others are dropping knowledge, I'm asking.)
     
  22. rcmodel

    rcmodel Member in memoriam

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    There is no formula that I ever heard of.

    The manufactures can't even all agree on the numerical order of all the powders in a burn rate chart.
    The book publishers can't even agree on what a MAX load is for any given caliber & bullet.
    Or the OAL it should be.

    I guess Quick-Load software would give you a guesstimate.

    But thats all I know of.

    rc
     
  23. ATLDave

    ATLDave Member

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    Thanks. That's all consistent with what I thought I knew, but figured I'd ask.

    BTW, one of the most puzzling experiences of my relatively-young reloading career was finding that two manuals had start/max loads for the same powder and very similar bullets that had NO OVERLAP. In other words, one manual's max load was under another's start load! That's when I decided that finding one set of published data would not generally be sufficient to me - I want multiple sources.
     
  24. greybeard57

    greybeard57 Member

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    I'm so new with reloading I think I'm moving backwards sometimes. :)

    With that said, I was wondering if those loads may have been measured differently? The CUP test is slowly being supplanted by the PSI test procedures from what I understand and the same manual may have both procedures listed for the same configurations. Just a thought.
     
  25. bds
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    bds Member

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    The CUP and PSI do not correlate with each other. I simply use them as different scales to gauge chamber pressures.


    The differences in published load data are from difference in barrel lengths, groove diameter of the test barrels, primers used, etc. which will affect the velocities/chamber pressures measured.

    A key example of this is Lyman #49 and the 40S&W load data which used larger .401" groove diameter test barrel instead of more typical .400". If you compare Lyman #49 40S&W load data with Hodgdon load data, it will be higher.
    Due to these reasons, when I am doing my initial load development, I will compare all available load data (and the test specs) and use the lowest start/max charges for my powder work up.

    This is what I do. If the working OAL that I am using for my load development is significantly shorter than the published OAL for the same nose type of the bullet, I will calculate the actual bullet seating depth (OAL - length of bullet = bullet seat depth). If the bullet seat depth is greater than say .010"+, I will incrementally decrease my start/max charges for my load development.

    Here's an example for 9mm Missouri 125 gr RN bullet (SmallBall) which is shorter with longer bearing surface which gets seated deeper in the case neck than other RN bullets with shorter bearing surface (see picture below and compare MBC RN to Dardas and ZCast RN bullets):

    [​IMG]

    For calculation purposes, I will use 1.125" as OAL for the CN bullet (.620" in length) and 1.080" OAL for the RN bullet (.565" in length).
    So based on my calculations, the bullet base will get seated .010" deeper with the MBC RN bullet when I use 1.080" OAL.

    Here's current Hodgdon load data
    So for my work up, I used 3.6 gr as my start charge and 4.1 gr as my max charge (I did work up to 4.4 gr but I got leading at 4.2-4.4 gr).

    As a comparison, 1999-2005 Winchester load data for lead 124 gr RN bullet (which doesn't list OALs) showed start/max of 3.3 gr - 4.0 gr. In the end, 3.8-4.0 gr of W231/HP-38 worked out for me.

    [​IMG]

    I may have been overly cautious with my powder charge reduction but thankfully I had the older Winchester load data to reference. For the lower pressure 45ACP loads, .010" reduction in OAL may not translate to much but for higher pressure 9mm/40S&W loads, I would reduce .2-.3 gr to start my work up and later may work up to published max to see how things go.

    YMMV
     
    Last edited: Feb 20, 2013
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