Just when you didn't expect it.
These low pressure roll crimp loads are built around the BP1044 wad and Herco powder. The "mild-mannered" version is listed in the 1250 fps range and rated close to 5500 psi.
And, yes, the "mild mannered" version is also a buffered load!
https://www.ballisticproducts.com/load05172023.htm