This just popped up on Reddit /r/Firearms, and I thought it should be shared here.
MCX Mandatory Carriage Assembly Replacement Program
https://www.sigsauer.com/press-releases/mcx-mandatory-carriage-assembly-replacement-program/
MCX Mandatory Carriage Assembly Replacement Program
SIG has found through extensive factory testing that in extremely rare instances, not reported in the field and extremely difficult to replicate, a condition may exist causing an unintended discharge....Although this has only been witnessed in 300 blackout, SIG has decided to upgrade all MCX models since the MCX is a modular platform and we want to ensure the quality and reliability of all products we manufacture.
https://www.sigsauer.com/press-releases/mcx-mandatory-carriage-assembly-replacement-program/