Gilmore, the reigning NFL Defensive Player of the Year, was involved in a collision in practice on Thursday, according to a source. He was a limited participant in practice that day, didn't practice on Friday, and had officially been listed as questionable on the team's injury report.
The Patriots (2-4) departed Saturday afternoon for their game against the AFC-East leading Bills (5-2) in Orchard Park, New York, and Gilmore isn't on the trip. Third-year player J.C. Jackson is projected to replace Gilmore, assuming the knee injury that limited him in Friday's practice doesn't keep him out.
The Patriots also ruled out rookie safety Kyle Dugger (ankle) and rookie offensive lineman Justin Herron (ankle) on Saturday. Both have been regular contributors for the Patriots this season. Herron was also placed on injured reserve.
In addition, the team previously had ruled out receivers Julian Edelman (knee) and N'Keal Harry (concussion), as well as defensive tackle Carl Davis (concussion). Edelman was placed on injured reserve Saturday after ESPN NFL Insider Adam Schefter reported that he underwent a precautionary standard knee procedure on Thursday morning.
"I don't think this is a season-ending situation, but we'll see. I'm not a doctor," coach Bill Belichick said of Edelman on Friday. "Hopefully he'll be back. He has worked awfully hard. Nobody is more competitive than Julian is, so he'll do everything he can to be back out there.
"We'll see how it goes and hopefully he'll have a good recovery and be back better than where he was before the surgery. That's the whole point of doing the surgery is that the situation will improve."
The Patriots made several other moves Saturday.
Rookie linebacker Josh Uche (second round, Michigan) and core special teamer Cody Davis were activated off the injured reserve list to the 53-man roster. Receiver Isaiah Zuber and defensive end Tashawn Bower were elevated from the practice squad and defensive tackle Nick Thurman was signed from the practice squad to the 53-man roster. Running back Sony Michel was removed from the reserve/COVID-19 list but remains on the injured reserve list.