Police have released more details about what was found during the searches in south Armagh and east Tyrone.
Also found were 25 kilos of home made explosives, an automatic weapon, a silencer, ammunition, three timer power units, booster tubes and a detonator.
The searches followed the arrest of three men in Keady on Good Friday.
The men were subsequently charged after a number of weapons - including machine guns and rifles - were found in a car they were travelling in.
They have not been charged in connection with the other weapons found in the follow-up searches.
The horizontal mortar found in the later searches contained more than half a kilo of Semtex.
There have been a number of significant arms finds by the PSNI since dissident republicans murdered Constable Ronan Kerr in Omagh on 2 April.
Days after the murder rifles, detonators, component parts for rocket launchers and explosives were found in the Coalisland area of County Tyrone.