If you want to keep calling this gun a Widowmaker, you'll have to shoot only married men.
The weapon alerts enemies (generates noise) in a 18 unit radius.
Take the .38 revolver, increase its damage and armor penetration, change the caliber to .45 and switch the appearance to your classy Wild West themed six-shooter, and you get yourself a .45 Widow Maker. It's practically the same gun as the .38th, but better in every aspect, except only that it's chambered with more expensive and rare ammo. It'll be your primary handgun for the majority of the time spent in Los Angeles where you can acquire it almost right away.