Sig has redesigned the “bolt carriage assembly” of the Sig MCX tactical carbine. This is great news. I stuck with the gun even after in TNP we revealed a serious flaw in the spring cup to retain the recoil springs. Several guns are held for long term testing in TNP, the MCX is one of them. Sig in their release notes that a remote possibility of slam fires is was also evident so the carriage assembly shows several changes. My recommendation, noted here, was to improve the “spring plate” maybe making it out of CNC milled 6000 series aluminum. I call it the spring cup and it had allowed the springs to pop out, detach from the recoil rods, and take the MCX out of action (see our video “Sig MCX Fails Unexpectedly” The new spring cup is pinned but still made of plastic I believe.
Sig immediately sent use new springs and spring cup (Gen 1 design) upon us calling them. These shooting videos show them installed here in action. These vids were taken prior to Sig’s release of the new assembly or at least me knowing of it. I still think the MCX failure was an anomaly but it did happen. If you own a MCX now can “Gen 2” it for free. Sig info below:
“SIG SAUER – MCX Mandatory Carriage Assembly Replacement Program
SIG SAUER is conducting a mandatory replacement of the carriage assembly in SIG MCX rifles. 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 we want to ensure the quality and reliability of all products we manufacture.
Stop use of firearm immediately, and visit the SIG SAUER website listed below 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 5-7 working days of the receipt of your parts at no cost to you. Please note total in transit times will vary based on geographic locations. 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. You may also contact SIG SAUER customer service at the number below with any questions if needed.
SIG SAUER is committed to addressing this issue in an expedited manner, and appreciates your support.
Firearm Registration –
For Customer Service – 603-610-3000: Option 2
For Instructional Video –
*Serial numbers 63C000044 – 63C003702 – Contact SIG Customer Service for instructions.
*If you have replaced your trigger group with an aftermarket trigger please contact SIG Customer Service for instructions.
*SIG SAUER Dealers should call designated Commercial Sales Support Representative.
*Any MCX rifle with a serial number ending in 25000 or higher is exempt from this program.”
Re-upload b. first version was screwed up, thanks!
