Jonathan Houseman, 32, allegedly asked machine operator Gavin Hastings whether he could help him buy a firearm, Birmingham Crown Court was told.
Mr Hastings said he could not and informed his boss, 29-year-old Brian McIntosh - who Houseman is accused of killing - of the conversation which allegedly took place two years before the killing.
Houseman is accused of murdering Mr McIntosh and Will Henry, 31 - who were found dead in a Range Rover at the Albion Works industrial estate, off Moor Street in Brierley Hill, on September 30 last year - over a £200,000 debt he owed them.
Taking to the witness stand, Mr Hastings said he knew Houseman and Mr McIntosh and Mr Henry too, although he only knew the murder suspect as a "colleague", whereas he was best friends with Mr McIntosh and a good friend of Mr Henry.
In cross-examination, prosecutor Michael Burrows QC said: "You told us, for two-and-a-half years you knew him. You worked with him at Mucklow Hill [in Halesowen].
"Is there a conversation you had with him looking back that is significant?"
He replied: "Yes, when I first met him. [He said] 'can you get hold of one of them' and made a gesture with his hands. I said 'I don't know what you are on about'."
Mr Hastings was asked to demonstrate to jurors what the gesture was, to which he made a gun sign with his hand.
He continued: "I said 'I don't know what you are on about' and he said 'can you get hold of a shooter'.
"I said 'I don't know what you are on about'. I told Brian what he had said."
Mr Hastings said he was left physically "sick" and shocked after he was told that Mr McIntosh and Mr Henry had been shot dead.
At the time, he was staying at Mr McIntosh's old house, and recalled members of the victim's family coming round.
He said a phone call then took place with Houseman, in which the defendant "started crying" at the news and said he "he couldn't believe it".
Mr Hastings said he received another call from Houseman around four or five hours later, in which the defendant was "still crying".
But he said that phone call was cut short after hearing a "bang" and shouts of "armed police, get out of the car" from the other end of the line.
Houseman, of no fixed address but formerly of Quarry Park Road, Stourbridge, denies murder.
Co-accused Richard Avery, 33, of no fixed address, who prosecutors say was planning the killings, also denies murder and perverting the course of justice.
Avery’s partner, 33-year-old Francesca Scott, of Lower Valley Road, Brierley Hill, is also on trial accused of perverting the course of justice after allegedly disposing of clothing or other items.
The trial continues.