New/Old Bullets??????

[Rabid Rich]

Have any of you ever heard of this outfit the "Fort Worth Firearms"? I was given two boxes of lead bullets containing 20 each of ".503 cal., 480 grain, Solid Nose, solid base, Pre-lubed" bullets called "Lonestar Slug".
I am also curious about what load I might use to get thesesuckers "movin for'ard mor'n backards" out of a .50 T/C Hawkin.

Thanks,
RR