Hello where would one find reloading data for a heavier 38/55 bullet. 280 grains.?

Thanks

Hodgdon's website shows data for 278 grain bullets with Accurate, Hodgdon and IMR powders.

https://hodgdonreloading.com/rldc/

Also, the Lyman Cast Bullet Handbook 4th Edition has data for 264 and 300 grain bullets, you could interpolate something from those.

Thanks Jim!

I really appreciate it.