Tim, I haven't read any published loads for short tens, but for 1 1/8 to 1 1/4 ounces of shot at 1200 fps or less, I don't think you want "a slow burning nitro powder" but rather a faster powder similar to what you would use in light 12 gauge target loads, like Red Dot. A slow powder like Unique or Herco with 1 1/8 ounces at 1175 fps through a big hole would create pressures so low that ignition would suffer, especially in colder weather. Herco and Blue Dot are for full power ten gauge loads of 1 1/2 ounces or more and pumped up velocities.
