I have a SBR'ed stainless sidefolder. have had it almost 10 years. I went thru all of the various front sights until I found and purchased a true ac556 front sight. granted, its blued, but its real.
I may have a stainless KAC556 front sight somewhere around here, if you are interested. I thought I saw one a few weeks ago in a pile of Ruger pieces-n-parts.