I purchased a bunch of estate sale IMR 3031 and it is an excellent powder for 308 Win gas guns. The pressure curve was a little faster than IMR 4895, and that was all to the good for the functioning of a gas gun. You want the powder to give the mechanism a quick kick and then the pressure curve to drop rapidly. It was not used for loading M2 ball in WW2, primarily I think, because old style IMR 3031 is long. I shot up all my old IMR 3031 in 308 Win and a bit in 30-06 and it shoots well.
Recently I purchased a keg for my 30-30 and found it is now a short cut powder. New style IMR 3031 shot very well in the 30-30. I think it will do well in the 223, in fact, any medium sized case. It will not give the highest velocity in 30-06 sized cases, but it was a commonly used powder for target shooting, back when the 30-06 was widely used.