Sig Taper Cap / Adapter

Tucker301

Groundskeeper
Banned !
Feb 13, 2015
9,494
23,366
Southern VA
Admittedly I haven't followed this subject and have likely missed something simple.
I thought finding an adapter for my MCX to convert it to 90 degree shoulder would be a simple matter of finding one online and clicking the add to cart button.

Not the case. They appear to have been discontinued? But why?
Have they been replaced by something else?

I found one here through the PX, but I'd sure like to know what bit of information I'm missing on this.