Ok more to report. Huge shout-out to osu92, he tested the 70gr RDF in an 18in clear ballistics gel block. No stated velocity, but impact was at 83 yards, so a reasonable distance. Attached are the pics:
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So as we can see, it has an ~4.5in neck before exhibiting good terminal performance characteristic of other "match" bullets like the SMKs and penetrating a full 14in+. Very fortunately as well, the neck has shrunk over 3in from it's 6.5mm brother above! The gel looks very similar to the mk262mod1 gel tests, which of course used the 77gr SMK. Unfortunately like the older SMKs the neck, while much shorter in .223, is still just a bit longer than most would like for use on some two legged or thin skinned game. While you do lose velocity stepping up to the 77gr TMK, you get a neck that is ~2in shorter. Whether or not that is a good trade really depends on what you are doing with the round.
So now the question is, what is the terminal envelope of the 70gr RDF? I believe the TMK window is 1800fps+ it will frag/deform. That will take more extensive testing, if anyone is up for it let me know.