Lots of powders will work well with .223 - right now you might just have to see what you can get your hands on and check that it's appropriate for .223/5.56. Many will work, but the most popular ones are fairly scarce at the moment. BL-C(2) and H335 are my favorites but there are many other good choices - H322, H4895, AA2015, AA2230, W748, Ramshot TAC just to name a few.
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