Maybe Coregon or someone elese can chime in on this, but I was able to purchase the MCX Rattler deflector from Sig Sauer in anticipation of removing the forward assist for a "quasi" Rattler look.  When I called Sig to purchase the remaining parts:  Deflector insert, roll pin, screws, the Sig rep told me he couldn't sell me those parts becasue they are only "armorer level" replacement components.  I explained to the rep that I attended the Sig MCX armorer's course but he still wouldn't sell the necessary parts.  Anyone have another option to obtain the remaining items?

I've found that calling back and talking to a different rep will often get you what you need.
That said, Midwest Gunworks often has small little parts like that.

Me too! I called in once and got a "no" answer on a barrel. Called back a few days later and "what credit card will you be using?" YMMV

I would think that attending the MCX Armorers course would qualify you for purchase. Maybe ask to speak with a Sup.? Nicely...

Just an update on converting the MCX Virtus without a forward assist. I could not get Sig Sauer to sell me the remaining components (metal insert, roll pin). In speaking with a Sig rep I deal with, he suggested removing the current insert and tranferring it to the Rattler deflector. Lo and behold the parts are interchangable so the only part you actually need is the plastic deflector housing and move the insert and pin over. Just use a vise with rubber jaw protects and a 3/32 punch to drive the pin out.