Many thousands of .38 Special reloads using 158-grain cast lead SWC and 5.0 Unique for several decades. Accurate, controllable, and effective for most uses. This has been my "go to" .38 Special load for decades, typically in the 850-900 FPS range with 4" barreled revolvers.
The increased resistance that comes with jacketed bullets (in the forcing cone and rifled bore) results in slower acceleration and lower velocities within the same overall operating pressures. Within the generally accepted pressure limitations of the .38 Special cartridge it is difficult to get a 158-grain jacketed bullet up to 800FPS, and that is marginal at best for any expectations of bullet expansion.
Properly made, sized, and lubricated cast bullets perform very well with lower overall pressures that are generally easier on the firearm (and the shooter), and serve most needs quite well. The jacketed bullets come into their own in the magnum calibers and high pressure loads (although many of us are perfectly content with good cast bullet loads in the 1200-1300FPS range when .357 magnum performance is needed, and actual performance on game animals is quite similar, at least in my experience).
