A demand from the neighbouring European Union that the Swiss toughen their gun laws has prompted a rare national debate over firearm ownership in the wealthy Alpine nation, which has a deeply-rooted gun culture.
While the government has cautioned that the new legislation is crucial to the non-EU country maintaining its treaties with the bloc, the proposal sparked a fierce pushback from the gun lobby and shooting enthusiasts, who gathered enough signatures to trigger a vote under Switzerland's famous direct democratic system.
But the most recent polls indicate the gun law reform will receive strong backing in Sunday's vote with 65 percent of respondents to the latest gfs.bern survey saying they support the move.
Brussels changed its own weapons laws two years ago following a wave of deadly terrorist attacks across Europe, slapping bans on certain types of semi-automatic firearms.
While not an EU member, Switzerland is bound to the bloc through an array of intricately connected bilateral agreements.
Bern has cautioned that a “No” vote would lead to Switzerland's exclusion from the visa-free Schengen travel region and also the Dublin accords regulating Europe's asylum-seeking process.
This would have far-reaching consequences for security, asylum and even tourism, and would cost the country “several billion Swiss francs each year,” it said.
However, the shooting enthusiasts behind Sunday's referendum claim the government warnings are “exaggerated”.
The campaign has charged that law change amounts to an “EU dictate” that reins in Swiss sovereignty and would “erase the right to own weapons” in Switzerland.
It also insists it would be “completely useless in confronting terrorism”.
The strong gun culture in Switzerland is partially tied to its tradition of national defence service, as most Swiss men undergo obligatory military service between the ages of 18 and 30 and are allowed to keep their assigned weapon when they are done.
It is difficult to know exactly how many firearms are in circulation in Switzerland, since guns are registered regionally and there is no national registry.
But according to a 2017 report by the Small Arms Survey, the country boasts the world's 16th highest rate of gun ownership, with some 2.3 million firearms in civilian hands — nearly three for every 10 inhabitants.
Under the new gun law, which has already been approved by legislators, semi-automatic weapons with high-capacity magazines would be listed as “banned”.
Collectors and sports shooters could still purchase such weapons, but would need to jump through more hoops to obtain an “exceptional authorisation”.
Another issue put to a vote on Sunday is a government proposal to overhaul the country's corporate tax system.
The reform, which would abolish some fiscal advantages for multinationals and also pump more cash into the country's pension system, also appears likely to pass muster with voters.
According to the latest gfs.bern poll, 59 percent of those surveyed were in favour of the reform, which already has the backing of parliament.
Polling stations in most places are set to open at 10:00 am (0800 GMT) and to close at noon, but most people in the Alpine nation vote in advance and final results are usually tallied by late afternoon.