A judge heard yesterday that Frank Schyvens and Michael Kartono had run a furniture shop, Belgica UK, in Bo'ness, West Lothian, but they had an acrimonious split in 2003.
Last March, Schyvens, 51, of Alva, Clackmannanshire, went to the shop armed with a revolver and demanded to be told by staff where he could find Mr Kartono.
He said he wanted revenge and that if Mr Kartono had been there, he would "pop him straight away".
He forced Stuart Edmonston and Joan Todd into a car and made Mr Edmonston drive away, but the police had been alerted and armed officers arrested Schyvens.
Schyvens has admitted assaulting Mr Edmonston and Ms Todd and placing them in fear for their lives. He also pleaded guilty to firearms offences.
Lord Mackay is hearing evidence to establish the background circumstances to the offences.
Schyvens told the High Court in Edinburgh that when he set up in competition to Mr Kartono, he had been pursued by debt collectors for bills which had nothing to do with him. There were many other incidents, he alleged, such as messages made from letters cut from newspapers. One had read, "We let you live till we decide you go with a bang". Another read, "Death by Christmas, ha ha ha".
Schyvens said he believed Mr Kartono had been behind the messages and the incidents. Mr Kartono denies it.
In March last year, Schyvens received another demand to pay a bill. "I had to go and see Michael about this. I do not know what I was thinking. I just needed to see him and demand of him to stop it. I had a few drinks before I decided to go," said Schyvens. "They (the staff) must have been very scared. I thought about it afterwards. I would like to apologise to them."
The hearing continues.