Wolf had a bad run of SPP with failure rates as high as 10% a few years back. I thought they quit selling SPP because of it and Tula took over. The primers went from brass color to silver and QC went off a cliff.
I still use Wolf LPP for practice ammo, but they are the brass color. I was getting them for $15.50 per K from Powder Valley and never had a LPP failure.