I was under the impression that the original IMR powders were all the same mix, just in different shape/sized granules. I'd have a hard time believing that a sane charge of 3031 ringed chambers with enough frequency to develop a reputation. I've not tried 3031 for reduced loads in anything, as there are better powders for my purposes, like 4198 or 4227. I can't imagine why it wouldn't work with at least 60% case fill though.
