If I had to wager a guess, I'd imagine they would make a MCX-specific trigger to negate the need for a "SSA specific" firing pin lock. I imagine that would be a benefit for folks who don't want to send their rifle back to Sig for the install or call them and ask for the appropriate part. A MCX-specific trigger would also reduce chances that folks experience issues and allow Geissele to better support them. I suppose it's also possible that Geissele is making a package with their own trigger and lock. Geissele hasn't released any other details that I could find but it'll be interesting to see what they come up with.Been running the SSA-E in mine for a while now. Even shipped back complete rifle for recall with trigger in it. Sig sent rifle back with upgraded BCG and the SSA-E still in it. With a work order attached stating the gunsmith "Performed mandatory carriage assembly upgrade with Firing Pin Lock for Geissele SSA trigger, function test and test fired with no malfunctions."
So why is Geissele making a specific trigger for MCX when SSA series works in it?
My MPX has same trigger and running flawlessly.