Is making קידוש on schnapps Shabbos, לכתחילה?
Rav Ari Enkin writes
While a superficial review of the laws of kiddush would lead one to conclude that one who recites kiddush upon whiskey and the like should be required to quickly drink a revi’it (approximately 4 oz.), just as is the case with wine, there are authorities who insist that this is not necessarily so. These authorities reason that such a relatively large quantity is not required when using whiskey for kiddush because it is simply not the normal manner or quantity in which one normally drinks such beverages.[Taz O.C. 190 & 210:1] These highly alcoholic beverages are normally enjoyed 1-2 oz. at a time and served in what are known as “shot glasses”. Since this is the normal manner in which these drinks are consumed, one would be permitted to recite the Shabbat day kiddush upon them in this way.[Maharsham 1:175, Minchat Yitzchak 10:22] In fact, one who treats a shot of whiskey as if it were a kiddush-sized serving of wine may be required to recite a “borei nefashot” after drinking even this small amount.[Har Tzvi O.C. 159]
Some suggest that the practice of reciting kiddush over a shot of alcohol evolved due to the scarcity and expense of wine in certain parts of Europe.[Mishna Berura 272:29] Since the situation has changed, many authorities assert that we should revert to the practice of making kiddush exclusively upon wine.[Shevet Halevi 5:32] Nevertheless, the custom of using chamar medina for kiddush is a strong one, not likely to ever disappear.
Rashbam in pesachim 107a explains that chamar Midina is only when there's no wine in the city. Most reishonim go with this requirment. Also the shulchan Aruch and mishna brura as well. The Mishna brura brings the custom of making kiddush on beer on shabbos day. Even after bringing the bidieved defence for it, says that it's still a mitzva min hamuvchar to use wine... The Mishna brura holds that even if you use chamar midina you should fill up a cup that can contain a riviis. Shabbos day one can rely that its 3 oz. And you should drink a malei lugmav which is more than half a riviis, which in this case would be 1.6 oz.