JB has stated that the so called bonding of the Hot Core doesn't appear to exist. The few bullets we've been able to recover seem to bare that out. With the oxidation rates of copper and molten lead, it would be hard to get the "solder joint" effect and get a well balanced bullet. That said however, I've been favorably impressed with the performance on our Kansas whitetails with the 87 Speer out of my old M99.
As to magnum velocities, I'd still rather keep them under about 2800-3000 fps at impact.
