Originally Posted by
call_me_ski
Could be attempting to make the handguards more rigid for IR lasers. Could be that some customers wanted the handguards harder to remove to avoid tampering by the lowest common denominator.
As far as parts availability. The MCX is not going anywhere. Sig still supports legacy customers and the legacy is upgradable with virtus parts. Not to mention that Sig has made all parts available other than the lowers. The MCX is easier to get spares for than almost every rifle other than an AR15.
Sig can be criticized for abandoning platforms and customers but the MCX does not seem to be one of those instances.