A replica machine gun was stolen from a vintage military vehicle at farm near Darmsden.
Along with the replica Browing .50 calibre machine gun, a metal gun feed belt containing used cartridges and two green army helmets were also taken from the barn.
A Suffolk police spokesman said the replica did not pose any risk to members of the public.
The incident happened between December 20 and January 7. Anyone with information should contact police on 101 or Crimestoppers anonymously on 0800 555 111.
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