Roscoe and DM,
I would consider the Partition HG but it is only available in 250gr. I am looking for the biggest chunk of jacketed lead at <1000 fps I can find. I would use 400 grainers meant for a 444 marlin if #1. They would fit the magazine of my 77/44 and #2. If I could find data for them.

Handloader,
I am not familiar with a LBT Heat treated bullet.

Thanks for the input guys