A way to test for a dangerous situation is to lock the slide back(check that gun is unloaded,no mag in gun),then holding the gun loosely,drop the slide release.The hammer should stay back.If it goes to half ####,or worse,follows the slide all the way down,it is in a dangerous condition.(note that this test is very hard on the sear/hammer interface so you dont want to do this repeatedly).Likely someone has tried to do a home trigger job either messing with the sear/hammer or more likely bending the sear spring to get a lighter pull,but now with not enough pressure on the sear(left wing of the sear spring as viewed from the back).Another possibility is that the trigger stop screw is screwed too far in.Hard to believe the gun left the factory this way.Either way,if your not comfortable working on 1911s,have a gunsmith look at it.Your gun is likely close to going full auto which can be pretty dangerous.