The men, from Magherafelt, were arrested as part of a National Crime Agency-led investigation.
A PSNI spokesperson revealed the 27 and 59-year-olds were detained on December 23 on suspicion of illegally possessing and importing weapons, as NCA officers executed a warrant in the Castledawson area.
He said: “Investigators were working with our Paramilitary Crime Task Force (PCTF).
“A number of firearms were recovered from the property and are now being analysed. A quantity of cash was also seized.
“The 59-year-old man has now been bailed pending further enquiries, while the 27-year-old remains in custody and is being questioned.”
NCA Belfast operations manager Gillian Shackleford said: “These men were arrested as part of an international investigation focusing on the supply of illegal firearms.
“Stopping the criminal supply of guns is a priority for the NCA, and working with our partners in the PSNI we are determined to do all we can to prevent such weapons reaching our streets.”
For those that aren’t already aware of what the PCTF is. Ourselves, HM Revenue & Customs and the National Crime Agency have established the Paramilitary Crime Task Force to tackle criminality linked to paramilitarism as part of the Executive’s action plan on tackling paramilitary activity, criminality and organised crime.”