Realistic suppressors in movies
 

I just saw John Wick 2 again and the Arsenal Strike One is used by Cassian seems a bit too small for it to actually effectively suppress anything and that made me wonder how often we see a suppressed gun in a movie and wondered if it was the appropriate size to actually work.

Smallest 9mm can I ever ran was this one:
http://www.breachbangclear.com/gemtech-aurora/

Quiet for about a magazine full of rounds. (Then you have to replace the wipe).
Cans are getting smaller every year, the one in JW2 looks similar to one I'm supposed to get in soon. The square shape acts more like a heat sink and has a bit more volume compared to a round can (at least in theory). Haven't seen the movie yet, but very few films use real cans and if they do, it's difficult to get the sound just right.