The Raiders have also signed RB Rod Smith and placed CB Dylan Mabin on the practice squad injured list.
McClain, 31, is a former third-round pick of the Panthers back in 2011. He lasted just over a year in Carolina before he was waived at the start of the 2012 season and later signed by the Patriots.
McClain had stints with the Texans and Cowboys before signing a four-year, $21 million contract with the Redskin in 2017. Washington released him after one year.
Since then, McClain has played for the Falcons, Cardinals, and Chiefs before joining the Raiders a few months ago.
In 2019, McClain has appeared in five games for the Raiders and Chiefs and recorded six tackles and no sacks.
Brown, 27, is a former third-round pick of the Bills back in 2014. He played out the final year of his four-year, $3,005,750 before agreeing to a one-year contract with the Bengals last year.
Brown agreed to a three-year contract worth up to $21 million with Cincinnati but was waived last month. The Raiders signed him to a contract soon after.
In 2019, Brown has appeared in 10 games for the Raiders and Bengals and recorded 54 tackles, a forced fumble and a recovery.
Swearinger, 28, is a former second-round pick of the Texans back in 2013. He lasted just over two years in Houston before he was waived at the start of the 2015 season and later claimed off of waivers by the Buccaneers.
Tampa Bay cut Swearinger loose during the 2015 season and he eventually caught on with the Cardinals. The Redskins signed him to a three-year, $13.5 million contract back in 2017 but elected to waive him at the end of last season.
Swearinger was later claimed by the Cardinals before being released a few months ago. He later signed on with the Raiders.
In 2019, Swearinger has appeared in eight games for the Cardinals and Raiders and recorded 48 tackles and two passes defended.