The defensive end, who was drafted 249th overall, was among four players cut from the team Saturday. Seventeen players were cut Friday in order to get closer to the 53-man regular season limit.
Sam was up against undrafted rookie Ethan Westbrooks for the fifth spot at defensive end, the St. Louis Dispatch reported.
Sam had two sacks during the preseason, including one on Cleveland Browns rookie Johnny Manziel.
Ultimately it's likely Westbrook's ability to also play inside at tackle swayed things in his favor.
Sam said he felt confident he'd make another NFL team. Other teams in the league have until noon Sunday to claim him.