That’s my point. *I* can grind a slot and drop my existing M18 FCU into it, but there is no cost effective way to do it without cobbling unless you already own a MS FCU. Yes, AB Prototype can cut for a FCU, but why is this even needed? Especially for the concierge guns.
One of the guys at the SIG Academy mentioned they were considering making all P320 FCUs manual safety compatible like the P365s, but that it would be a running change at some unknown point.