Setting up M4 mag for non 308 cartridge

Discussion in 'Gunsmithing' started by bigfish27, Jun 24, 2015.

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  1. bigfish27

    bigfish27 Member

    Mar 29, 2012
    I am trying to get a M4 magazine setup to feed 224 Weatherby rounds in a 308 magazine. COL is to long for a 223 magazine.
    One cartridge feeds fine. Two or more the cartridge feeds but the effort is really high. I think the answer is trimming the spring. Is this done by trimming small until it works or is there some way to get in the ball park quickly?