Any more pics? Usually the bolt recess is a giveaway if it's been sanded. The recoil lug is installed backwards.
Initially appears to be a righteous bolt mismatch.
Under 1k? Good deal. What are they asking?
Decocked! Everyone does that eventually, it seems.
Hook the sear on the edge of a board, edge of workbench, etc. Pull it back and rotate the safety up, then release pressure.