Indeed. Granted, he was still brainwashed as the Winter Soldier at the time, but it was still a harsh fate for Jack. If I recall right, Bucky ended up fighting "Commie Smasher" Cap back when he took over after Steve's seeming death following the end of Civil War, and a lot of "Commie Smasher" Cap's motivation for fighting him was that Bucky killed Jack, who was his partner.