I tried out a little Glock 42 today at the range and compared it with my R9. The G42 is about 1/2" longer, but other dimensions are about the same. The G42 is a little lighter, and it is 2x as accurate as my R9 ( with the G42 I was getting 5~6" 5-shot groups at 25yd, off hand; To get the same size groups with my R9 I had to reduce the distance to 12yd).
Which makes me curious, how accurate is the R380?