My only comment is. IF one is running a "pistol" why add the extra 1.5-2" of length to something you wanted as short as possible. IF you're considering a law, or other folder like it.
I added the law side folder to one of my sbr's, stayed on about 30 minutes before it was removed. For side folders, i went with the foxtrot mike bufferless 12" uppers with a sig folder.