Revolver or Semi-Auto?
About when did you buy it and was it new?
Taurus had a 745, 845, and 945, but I think they were all more than 5 rounds. You still see them available on the Internet from time to time. They have some smaller 1911 style guns, but those too I think are more than 5 rounds. It sounds like one of their ACP revolvers, but I don't recall ever seeing one in .45 ACP.
Wow, Just as I was pressing enter, I actually read the end of your post where you said revolver. (Not everyone on this forum is extremely bright!)
Try this link below. Maybe it was a .45 Tracker: