Police have been searching land around the property in Wyverstone Police said they were initially called to the house over an allegation of assault, and then carried out a search warrant.
Specialist search teams from Suffolk Police and officers from the Metropolitan Police are continuing to search the house, outbuildings and land, a spokesman said.
"It is anticipated that due to the number of outbuildings and area of land to be searched, officers could be at the scene for a further week to a fortnight and a cordon will remain in place during this time," the spokesman said.
A number of controlled explosions have been carried out, with more expected to make items safe.
The Ministry of Defence has also been called on for its "expertise" due to the "nature of the weapons being recovered".
Mr Arnold will also appear before Bury St Edmunds magistrates on Monday, accused of two assault charges.
A 45-year-old woman arrested on suspicion of possession of a prohibited firearm is on bail until 21 May.