I know that the following is an old, old question.
But the answer is valuable to even today's shooters.
It adds weight to the pistol as a steadying device, for shooting with only one hand at 25 and 50 yards.
Muzzle-heavy pistols feel steadier in a well-practiced hand.
Some of you have sufficient experience to know that, in NRA-bullseye-style competition, muzzle-heavy rifles also offer an advantage.

