Decapitating zombies with the shotgun

I have been playing the Resident Evil Remaster on Xbox One, which somehow scares me more as an adult than the original did as a kid.

In the original, you are able to decapitate a zombie instantly by aiming upward and firing when the zombie is directly in front of you, using the shotgun. This made dealing with zombies very easy and also made the Beretta redundant.

I gave it a go in the remaster and it seemed to work a couple times, but I've also just had it fail twice in a row; the zombie just acted like it received a normal shot to the body. It didn't seem like the damage was much higher than the Beretta either (barely double given it took 3 shots with the shotgun and around 5-6 with the Beretta).

How does this trick get treated in the remaster? Is there only a chance for decapitation now, or have I been doing something wrong? Maybe you need to get them extremely close or have perfect aim in the remaster?

Note I have never played the 2002 Nintendo remake so I'm not sure if this problem carries over from that.