There are some
comments on the copper solids here. They indicate they have a lot of length variation and non-match accuracy without specifying what that is exactly. They mention these bullets are long for their weight, which is to be expected since copper is less dense than lead. It also means they need to be spun a little faster than the lead core versions. Where a 12" twist is fine for the Hornady 55's with their lead cores, these copper solids may want a 9" twist or faster. The reviewer who tested them didn't say what he had.