I see Pete posted as I was writing and thinking about it a bit more a lot of our loads are 12ga loads we're using in the 10. Unique is used the 10, 12, 16, 20, and the 28ga so it would seem to reason it's quite an all around powder. If RD and GD will work in the 10 with a 1 1/8 oz there's no reason to think Unique wouldn't also work. You may have to go up a grain or two to get a clean burn, but I'd first try the 23 to 24grs and check the barrel for unburnt powder. Let us know.
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Paul Harm
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