Been loading some 9mm with Sellier & Bellot primers. They are the only pistol primers I had. The box was marked "4,4 SR Boxer For Rifle, Pistol, or Revolver Cartridges". In three different pistols, we've had 10-20% failures to fire. Some have fired on the second try and all are showing good firing pin strikes. The factory ammo I stumbled onto a while back has all fired without fail so it's not a gun issue. Are they just crap primers? What say you reloading gurus?