There'sa coupla different theories but the real world has a way with theories.
The S&W 640(marked 642,might be a collector) here likes my old duty load. That's a 110 gr JHP +P. This load does shoot a little low,and the fireball in low light is rather impressive. It's easily defensible in court, and I've a fair amount of it here.
It also likes the old FBI load, a 158 gr SWCHP +P, but recoil control is difficult.
Following something the NRA wrote about decades ago,I tried target WCs. Recoil is light,accuracy is excellent, and that 148 gr pure lead bullet should deform nicely even at the low velocities possible with that short bbl.The square shoulder on the projectile helps energy transfer too.