I've used slower powders than recommended for my mini 14 slower speeds but ran the gun just using what I had during lean times. keep looking on line for powder. late last nite member here posted. Gaff&Sons had h4350 needing some jumped on it. none of my lgs have anything same as you. hazmat was only is 12.50 good luck don't give up yet.Thanks for sharing this... I'm thinking about selling my 5.56 stuff only because I have primer, brass and bullets, but can't find powder.