It wouldn't be of much use if there wasn't.
Can't think of a reason not to. If you don't trust yourself or your weapon, you shouldn't carry.
Texas Ranger Charlie Miller was minding his own business when a concerned citizen came up to him, noted the hammer cocked back on the big 1911 dangling from the Ranger's belt, and asked, "Isn't that dangerous?" Charlie replied, "I wouldn't carry the son-of-a-bitch if it wasn't dangerous."
When you are carrying ouside of your home, is there a round in the chamber?