My Uncle Mike's pocket holsters came in today from Midway.
The Uncle Mike's #3 and #4 pocket holsters are very similar, with the #4 only slightly larger.
I purchased the #3 mainly for my J-frame revolver, but it can also be used for the standard Bersa Thunder 380! This has been noted elsewhere in this thread.
Though the BT380 fits okay in the #3, there's a better fit with the #4. The gun's a bit snug in the #3. The gun appears slightly large for the design of the holster #3.
So my recommendation would be to definitely get the UM #4 for the BT380. Product code is 8744-4.
BTW, they're nice holsters for the money. I'm pleased. Both enable a draw without coming out of the pocket and they're nicely constructed, and made of smooth material.
Hope this helps.