Uncle Tim did some number crunching. Under various sets of FIG rules the lowest scoring apparatus for these nations was …
Russia since 2006 = Pommels
USA since 2006 = Pommels by a MILE 😦
Japan since 2006 = Pommels
China since 2006 = Pommels
Russia under the 10 = Pommels
USA under the 10 = Pommels
Japan under the 10 = Floor
China under the 10 = Floor
See the details on Uncle Tim Talks Men’s Gym – MAG: What’s Your Country’s Worst Event?
If you discount Pommels, Horizontal Bar has been Russia’s weak apparatus for decades.