Back in the early 90's Taipan used to make 300 grain bonded core bullets in .458 which were meant to run at 45-70 velocities.
I ran them up to 2700 fps in my old 458 mag which of course was way too fast, and they flattened out real quick.
Could have run them faster still but there was no point.

Some later 300 gn Taipans which I bought just had a conventional core without the bonding.
The bottom photo showing 6 bullets shows the bonded cores in the bottom row and the later conventional cores in the top row.