40 S&W OAL?

Discussion in 'The Ammo & Reloading Forum' started by mongo, Sep 29, 2009.

  1. mongo

    mongo New Member

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    I am loading 40 S&W for my SA XDm 40. Today I tried a little experiment with the OAL. The Lyman book says 1.135. So I took an empty case and seated a 155gr lead cast bullet long and dropped it in the chamber and closed the slide slowly into battery. I pulled the bullet out and measured. It came out to be 1.162. I did the same with a 180gr JHP and it came out to 1.187. 1.162 is about the longest i think because at 1.187 the bullet rubs the front of the mag. Now the question is, would 1.162 be safe? I did not notice any rifle marks on the bullet and I have read that ideal is about .010 off the landing. So someone please give me some guidence.
  2. woolleyworm

    woolleyworm Active Member

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    This was probably in reference to loading for rifle loads. The listed 1.135 should be followed for your pistol loads as the max OAL. When you go to moving a bullet deeper or shallower in the case, remember, it will affect your case volume. This isn't such a drastic difference in percentage of case volume when you're dealing with a 300 win mag, but with a .40, it's a much bigger %. An increase in case volume can be just as bad as decreasing, although decreasing volume is much more likely to cause a KB, the results can be equally disastrous. At 1.162; you'd be .027" over listed max; this results in an approx .08cc increase in case capacity which is approx a 11% increase in volume. I'll have to double check my math when i can get a calculator and some id measurement on some cases; but I am pretty sure i am in the ballpark here.

    Keep it safe and have a great one,

    Woolley
  3. mongo

    mongo New Member

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    Thanks for that reply. Right now I am seating at 1.130-1.135.
  4. mongo

    mongo New Member

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    I found this while researching to. the link is also below. Its an IPSC article. Also, if you read through that article, there are guys loading as high as 1.235.

    Cartridge Overall Length (OAL)
    Many of the .40S&W handguns in use were developed from 9x19 handgun ‘roots’, and the SAAMI maximum Cartridge Overall Length ( 1.135”) for the .40S&W was set to accommodate the limitations of the magazines available for those designs. With the use of the .40S&W in 1911-pattern guns, the magazines will accommodate much longer OALs, and in many cases these longer cartridges will feed better in those guns. Many of the loads listed below were for OALs greater than 1.135”, and those without specified OALs from reloading manuals are to be assumed to be for loads no longer than 1.135”. Reducing the OAL of a load which is already at or above maximum pressure will drastically increase the pressure, possibly resulting in spontaneous catastrophic disassembly of the cartridge and gun!


    http://www.k8nd.com/documents/hl40sw.pdf
    Last edited: Sep 30, 2009