"Powerful gun can be loaded with .357 magnum rounds."
The Colt Python has gotta be one of the better weapons of the game. With it you can feel confident to take on most opponents with ease. The Colt can take the head off a zombie, kill a hunter in a shot or two, and even knock around a Tyrant with little problem. It's awesome firepower makes it a good weapon in your collection, but it's lack of ammo can hinder your use of it.
With the Directors Cut edition, beating the advanced/arrange game in under 3 hours will give you the Colt Python with unlimited ammo.
The Colt Python holds one full round of six bullets. Ammo is very rare until nearer the end of the game, so I suggest only using it when you really need it.
Originally concepts have shown that it was planned that some of the ammo in the game would have been Dum Dum rounds, but these were removed before the game went out.