Man good luck with the SCAR thing and good luck on the Sig for that matter. For what it is worth give Mike "ABLE COMPANY" a call at 636-458-7757 or Bill at the POWDER HORN at 802-878-2865 on the SIG 556 Rail, hope that helps bro. BTW I have come up craps on a SCAR at every turn too... :'(
I've recently seen SIG 556 pistols at Get Some Guns LLC, and Dougs Shoot and Sports; both are located in Utah
I've only ever seen 1 SCAR locally. They are still rare as hell on the street. Gunbroker is your best option, but you have to be willing to take it in the butt big time, because they sell for $5000-6000 on average.