.357 Sig and .40 Glock barrels interchange. In order to use a 9mm barrel in either you need a 9mm conversion barrel. The OD of the 9mm barrel is approximately .020 smaller than the .40/.357 barrel and will not work properly. This thread needs to be in Parts and Ammunition. Maybe a moderator can move it for you.
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I have an OEM G19 barrel if this is what you need. I do not know what you are wanting to put this into, but it will only fit in a G19. As JBP55 pointed out, you will need a conversion barrel if you are trying to convert the G23 to a 9mm. WILDMAN aka Danny