The owner of the weapons was interrogated earlier this week but later released, Bern cantonal police said on Wednesday.
It was the man’s behaviour that raised suspicions, police spokesman Andreas Hofmann told news agency ATS.
Questioned as part of a routine check on privately owned firearms, he failed to respond within the deadline and was unable to produce the correct papers.
Around 20 police officers, experts and army specialists took two days to search the property and take an inventory of all the guns and ammunition found there, reported ATS.
Quite how and why the man had amassed such a stockpile of arms is yet to be determined.
Police are now in the process of assessing which weapons, if any, he legally owned and therefore whether he has broken the law or not.
Interviewed by Blick newspaper, the owner of the weapons, identified as Peter Abplanalp, protested that he had done nothing wrong.
The weapons "are all right" and were causing no danger, the retiree told the newspaper.