450Bushmaster.net

Lehigh defense makes a .452 265 grain bullet. Has anyone tried reloading and what kind of results did you see?

Not that i'm aware of.
If I was going to try loading it, I would start with low charges for 300gr bullets. If it has a true diameter of .452, and no driving bands, it's probably going to have a lot friction. Might be a decent candidate for A-1680, or something similar (CFE BLK or Shooter's world blackout).

https://www.lehighdefense.com/all/452-c ... 5gr-bullet

is this what you're referring to?

Notes MUZZLELOADER ONLY BULLET (SABOT REQUIRED)

Yes that looks like it.