What’s your OAL?
It’s possible that your load is compressed too much. My Hornet loads, fired in a falling block single-shot are at 1.190 or thereabouts IIRC. I’ve noticed in articles about the Hornet where they use a repeater, the charges are a bit lighter.
JB says that pressures from rifle loads generally go down when you seat bullets deeper (to a point, anyway) because due to the progressive rifle powders used. The Hornet is almost a straight case, and generally uses pistol powders. Looks more like a pistol round to me.
You might post this inquiry in the Gunwriters’ forum where JB will be sure to see it. He knows a lot about the Hornet!
