I use the Wolf. Powder Valley had them listed as "5.56 primers" but the box says "small rifle magnum" so whether the wolf is milspec or not I don't know. But they seem to shoot quite well, and a lot of high power shooters are also using them.
They have worked so well I'm thinking about getting some Tula or Wolf 7.62 spec primers for my large rifle primer needs. For a third the cost of CCI-BR2s I don't think I would be unhappy unless my groups really opened up.
Machine guns are awesome until you have to carry one.