The implied gun ownership rate given by the firearm suicide rate in Hungary, for example, is rather high. It is also surprisingly high in Austria. Neither are like the US of course, but unless the primary reason people own firearms in those countries is for suicide, more people own guns than you may imagine.
Granted, I did research on proxy gun rate estimators many years ago, using even older data, so it is possible that things have changed but I don't see why that would be the case.