The firearm, an air rifle, was seized from a traveller site just off Armthorpe Road, Armthorpe on Tuesday afternoon when armed police executed pre-planned warrants in the area.
A South Yorkshire Police spokesman: "Police in Doncaster have seized an air rifle, following pre-planned warrants executed.
"At about 4.30pm, armed officers searched a caravan site just off Armthorpe Road, where the weapon was recovered from.
"The warrants are part of ongoing work to tackle armed criminality.
"No arrests have yet been made."
Residents have also reported seeing a heavy police presence in Amthorpe last night.
South Yorkshire Police have been contacted for more information on whether this is connected to the ongoing operation to tackle armed criminality in Doncaster.