Grant Wilkinson, 34, was convicted of seven offenses of converting and supplying firearms after he learned to adapt replica weapons into live ammunition guns, The Daily Express reported Thursday.

"The scale of this criminal enterprise is unprecedented in this country," said Judge Zoe Smith in passing sentence, which requires Wilkinson to serve at least years before being considered for parole. "The roll call of deaths and injuries is horrific. Some 30 to 40 of these weapons are still unaccounted for and regrettably but doubtlessly, the roll call of death and serious injury will continue to rise."

Scotland Yard is offering a nearly $20,000 reward for information leading to the capture of 40 Mac-10 sub-machine guns that haven't been recovered, or for information leading to the arrests of criminals who have used them, The Times of London reported.