Charlotte Hart, 19, and her mother Claire, 50, were killed by Lance Hart, 57, near the Castle Sports Complex in Spalding, Lincolnshire, in July.
Mr Hart then shot himself using the single-barrel shotgun days after Mrs Hart had left the family home after a breakdown in their marriage, an inquest at South Lincolnshire coroner’s office in Boston heard.
Coroner Paul Cooper concluded the deaths of Charlotte and Claire were unlawful killings and Mr Hart’s was suicide, adding: “He knew exactly what he was going to do.
“It was a single barrel shotgun, so it was not a question of him just shooting his wife, he then had to unload it, put another cartridge in and shoot it again.
“In my view, this was a cold, calculated, scheming man who went out and deliberately murdered his wife and daughter.
“If he had lived... he would have been charged with murder, unfortunately he didn’t live to face the consequences of his actions. He took his own life.”
In a statement read by Detective Inspector Helen Evans on behalf of Ryan and Luke Hart, sons of Claire and Lance, she said: “Charlotte and our mum were our inspiration and purpose in life.
“They were the two most virtuous and beautiful people we have ever encountered. It is not possible to describe how unfairly and how cruelly they have been taken from us.
“Our world is a darker place because they have gone.”