She also admitted the sawn-off shotgun's shortened barrel and the ingredients of the ammunition were not taken into consideration in her estimate, when questioned by defence lawyer Philip Hamlin.
"[But] considering all the factors, my best estimate is about 30cm," she said.
Sanft's defence team says he never deliberately aimed the weapon at his daughter.
Hamlin says Sanft believed the shotgun was harmless and that it accidentally went off in his hands while he was waiting to throw it into a rubbish skip. The prosecution accepts Sanft did not intend to kill his daughter and was surprised when the shotgun fired.
Crown lawyer Katie Hogan said Sanft was guilty of manslaughter because he recklessly pointed a sawn-off shotgun at his daughter and pulled the trigger, perhaps to scare her, because she began playing up by jumping on a couch.
She said Sanft failed to check if the weapon was loaded or if its safety catch was on.
The trial continues.
- NZN