I've been doing some more research on this event and I came across more details about the Sumner County, TN tornado that I thought I'd share. I've always felt that it probably deserved an F5 rating, and I think it's a pretty convincing case now. Contemporary reports from The Knoxville Journal make several extraordinary claims about the damage in the area between Keytown and Oak Grove. As I wrote in my blog article, all eight members of the Allison family were killed instantly outside of Graball, as was a neighbor who was attempting to seek shelter at the Allison home. The victims were scattered for more than a quarter-mile from the home (which was swept completely away).
What I didn't know at the time was that the bodies were completely mangled to a degree normally only seen in the most violent of tornadoes. This is kinda graphic, so you may not want to read it if you're squeamish. The mother was decapitated and partially skinned, the two youngest daughters were "torn into sections," and most of the bodies were so badly torn apart that there was really no way to identify the remains. Surviving relatives essentially just used a mass grave.
Significant ground scouring was reported just to the southwest of the home as well, and "every vestige of plant life" was scoured from the ground in a wheat field further to the northwest, which also suggests an extraordinarily violent tornado. In addition, the newspaper reported that even concrete and stone foundations were scoured from the ground, broken apart and scattered at several locations between Keytown and Oak Grove. I don't know whether I buy that since newspapers tend to exaggerate and/or misunderstand what happened, but it certainly caught my attention. I've heard claims of various tornadoes "scouring" foundations from the ground - 1974 Guin, AL; 1977 Smithfield, AL; 1997 Jarrell, TX; 2011 El Reno, OK and Hackleburg, AL being the most common ones - but I've yet to see photographs or other reliable evidence and I think the likelihood is quite small.