SIG Sauer is conducting a mandatory replacement of the carriage assembly in SIG MCX rifles. According to a statement from SIG Sauer, 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. Failure to follow the loading procedures and basic rules of safe firearms handling outlined in the user's manual has the potential to cause serious bodily harm or death. 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 to ensure the quality and reliability of all products they manufacture. Certain serial numbers are exempt from this program.
If you own one of these firearms, a SIG Sauer has issued these instructions:
Stop use of firearm immediately, and visit the SIG Sauer website as soon as possible to register your firearm, initiate the process and view a video explaining how to change out your carriage assembly. SIG will send you a prepaid box to return your complete carriage assembly to the factory. A new assembly, designed with the firing pin locking mechanism, will be shipped out to you within five to seven working days of the receipt of your parts at no cost to you. SIG will also send you a $50 gift voucher for any inconvenience this may have caused. This upgraded carriage assembly addresses this potential issue while enhancing the performance and longevity of your rifle. 
For all of the details relating to this issue, visit sigsauer.com
