While Switzerland doesn't belong to the EU, it is part of the bloc's Schengen Area which is a zone that can be visited without a visa or passport by citizens of 26 European nations.
Following terrorist gun attacks in Paris and Brussels in 2015 and 2016, the EU tightened gun rules, known as the "EU Gun Ban", the bloc encouraged Switzerland to comply with its laws.
The projections from the gfs.bern polling outfit saw the measure passing in the binding referendum by a comfortable 67-33% margin.
If Switzerland refused, the country could have been excluded from the Schengen Area.
But what are Switzerland's current gun laws and how might they change from this referendum?
What are Switzerland's current gun laws?
Firearms legislation in Switzerland is comparatively liberal, more similar to gun politics in the United States than to that in the European Union.