I have experience with an NAA Pug (22 WMR) and a NAA 22LR/22 WMR convertible mini. I have shot a lot of magnums through the Pug. It was very reliable with Speer Gold Dots, but lately I have gotten occasional failures to fire with the same batch of ammo. I think it is going to have to go back for service. I think it is wise to get a model with the cylinder pin assembly that the Pug and Black Widow have because the ball detent on the standard versions appears to experience some wear if you shoot them a bunch with magnums.
One other thing that is a disadvantage of the design is that you really need to practice cocking the gun under stress because it is not hard to fumble that with such a small gun.
I also think that Montana Marine makes some valid points about the size of the Black Widow in relation to other more effective firearms. If you really need something small, the Pug may be better.
Finally, if you use a thumbs forward grip normally, beware of the cylinder gap with your support hand thumb.
They are fun little guns but they have limitations.
Cheyenne nails it as per usual.
Smallest gun I’ll ever carry as a BUG, is my LCP 380.
Mine stays loaded with the Buffalo Boar Hard Cast load.