Frederick Thomas and Dan Roberts are set to be sentenced Wednesday. The two pleaded guilty in April to conspiring to get an unregistered explosive and an illegal gun silencer. They each face up to five years in prison and a $250,000 fine.
They are among four men arrested in early November after at least seven months of surveillance by an undercover informant who infiltrated their meetings at homes, during car rides and a Waffle House restaurant.
Co-defendants Ray Adams and Samuel Crump are charged with conspiring and attempting to make ricin and are moving toward trial.
Thomas and Roberts agreed to cooperate with authorities.