I didn't like the way the 380CC could shift about in the UM#4, so I bought a UM#3 to see how it fit. What I learned was that
the #4 is about 3/8" wider than the #3, and all other measurements (angle of opening, overall height, etc.) were the same. Here's how they "stack up" in a single pic:

Here's
how the 380CC fits in the #3 - there's no "rocking" movement possible:

Here's
how the 380CC fits in the #4 when the barrel is parallel with the holster sides (rocked forward):

And here's what I didn't like -
the 380CC "crooked" (rocked back) in the #4:

With the 380CC in the "crooked" position, there's a full finger width of space between the rear sight and holster.
Hope this answers the questions of potential buyers.
M D "Doc" Nugent -
carcentric.com