SWAT: Elite Force is a massive overhaul of SWAT 4: The Stetchkov Syndicate, making it into a more realistic tactical police simulator.
v5 will see a big shift in breaching mechanics, that will later be revised upon in v6.
For starters, broken doors can now be closed, and even wedged. They cannot be locked, for obvious reasons.
Any shotgun can now breach doors. A door's ability to be breached depends on the material of the door (wooden doors are easier to breach than metal ones), the type of ammo you are using (slugs are less effective than buckshot), and whether or not you are using the breaching shotgun. The breaching shotgun always breaches the door on the first shot, regardless of the material of the door.
Lastly, breaching shotguns will no longer launch the door open - this is incredibly unrealistic. Only C2 will launch doors open with force. You will need to shoot the lock and then open the door.
AI controlled officers cannot (as of yet) use anything other than the Breaching Shotgun to open doors with.