The army has opened an investigation after “losing” between 300 and 500 assault rifle cartridges, the ATS news agency reported on Monday.
The investigation should determine whether the ammunition has been lost, stolen or is the result of an accounting error.
“All possibilities will be examined,” military police spokesman Tobias Kühne told ATS.
Ammunition does disappear from time to time, he added.
The incident comes two months after a batch of explosives, grenades and detonators disappeared from an infantry school in Aarau.
At the time an army spokesman said such occurrences were “rare, thankfully”.
Speaking to ATS on Monday Kühne said there was no news in that investigation.
In a separate case prosecutors in St Gallen said on Monday they traced a batch of stolen army munitions to an address in Kaltbrunn earlier this month.
Its 22-year-old resident admitted he stole the ammunition during his military service, reported news agencies.
He also had a stash of 150 pyrotechnic devices, banned in Switzerland, which he said he bought on the internet and had delivered to Germany.