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LW 357 Sig conversion barrel in G20

Discussion in 'General Glocking' started by NM Mountainman, Jul 1, 2010.

  1. NM Mountainman

    NM Mountainman

    Likes Received:
    Aug 16, 2006


    Thanks for answering questions about Glocks in this forum.

    I am considering buying a Lone Wolf conversion barrel chambered in 357 Sig for use in my Glock 20 (Gen 3). I intend to use the Glock 20 with 357 Sig barrel as a range gun to get acquainted with the 357 Sig cartridge. I plan on using the factory magazines designed for the 10 mm, and I plan to shoot mostly handloads with 125 gr and 147 gr jacketed bullets. My questions assume this handloaded 357 Sig ammo will be used only in my Glock 20 with the 357 Sig conversion barrel. (I do not own another 357 Sig pistol.) Assuming my handloads stay below the max recommended pressure for the 357 Sig, what weight recoil spring would you recommend?

    As you are aware, the Max OAL for the 357 Sig is 1.14" , and the Max OAL for the 10 mm is 1.26" Thus a standard length 357 Sig cartridge could have empty space (up to .12") between the front of the bullet nose and the front edge of the magazine. Suppose I want to take advantage of the extra space in the magazine to load the 357 Sig to a max OAL length of 1.24" ( or with the base of the bullet even with the bottom of the case neck, whichever gives a shorter OAL.) The extended length 357 Sig ammo would be plainly marked for easy identification.

    Will the Lone Wolf conversion barrel chambered in 357 Sig accommodate ammo with an OAL of 1.24"? Would there be any advantages to increasing ( up to a max of 1.24") the OAL of the 357 Sig in this way? Would I need to add a little more powder to get the same velocity as standard length 357 Sig ammo? Are there any good reasons why I shouldn't increase the OAL of my 357 Sig handloads to a max of 1.24" for use in my Glock 20 as described?

  2. JR

    JR Moderator Millennium Member

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    Dec 29, 1998
    Oldtown Idaho USA
    Use the factory 17lb recoil spring. If your brass is flying 10 feet or more, add more weight. If your brass is rolling off your knuckles, reduce the weight. Ideally you want the brass flying 2 to 4 feet away.

    Sure, you have more room in the G20 mag so by theory you could long load the round. Problem is, the barrel would have to be throated and I am not sure the longer load would feed reliably. I am guessing it will stick into the top of the chamber.