Forensic investigator Col Johannes Vermeulen was explaining to the court, under questioning from prosecutor Gerrie Nel, at what angle he believed the bat struck the door.
Pistorius broke the door down with a cricket bat after he shot his girlfriend Reeva Steenkamp through it, apparently thinking she was an intruder.
He argues he kicked at the door after putting his prosthetic legs on.
Vermeulen referred on Thursday to a photograph displayed in court to make his point. It shows Vermeulen holding the bat against the door at an angle.
He told the court some material from the door had rubbed off on the toe of the bat as it struck an edge of a panel in the door.
Judge Thokozile Masipa interjected: “Can I just have a look?”
A court official held the bat up for her to see. She peered at it, before it was passed to her two assessors.
The door and the replica of the cubicle, complete with a toilet, cistern, and magazine rack, was set up next to the witness box in court GD.
Four bullet holes are clustered on the right side of the door, just under the keyhole. The toilet is to the left of the door.
Vermeulen is the commander of the material analysis sub-section at the forensic science laboratory.
Pistorius is accused of the premeditated murder of model and law graduate Steenkamp in his home on February 14 last year.
He is also charged with illegal possession of a firearm and ammunition, and two counts of discharging a firearm in public.