In the testing we've done here, it does seem that Universal Clays burns at a lower flame temp than Unique. Of course we don't have equipment to quantitatively measure this here, but in our experience and test bear out your postulation.
Interesting too, I believe AA #5 to have an even lower flame temp than either Univeral Clays or Unique. A powder well worth it's place on the loading bench for mid range bullet weights in a broad spectrum of applications.
Flame and "face slapping" has increased since I had my RSRH ported. I also think it is more noticeable because of the scope requiring my eye and head being higher to the bore-line and more exposed. Unique is a little worse than Universal.
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