You can shoot through doors

[NALStudio]

Because the bullet comes from the tip of the barrel, you can push it through a door and shoot

[NALStudio]

You can shoot through doors without that even.......

[NALStudio]

Bullets just go straight through....

[NALStudio]

Bullets going straight through doors was because the bullet moved too much in between collision checks and thus no collision between the bullet and the door could be detected.

A smaller resolution was implemented to combat this issue, but the performance is currently much worse.