Is ばかり the same as たところ in the sense that the action must be voluntary? e.g. Winter just ended, could you use ばかり?
Both 「ばかり」 and 「ところ」 can be used to describe the endings of either voluntary or involuntary actions.
It is perfectly grammatical and natural-sounding to say all of the following:
・「やっと冬{ふゆ}が終{お}わった(ばかり/ところ)です。まだ海水浴{かいすいよく}には行{い}けません。」 "Winter has just ended at long last. We couldn't go bathing in the sea yet."
・「今{いま}、晩{ばん}ご飯{はん}を食{た}べた(ばかり/ところ)です。おなかが一杯{いっぱい}です。」 "I've just finished eating dinner. I am stuffed."