Took WK TO THE RANGE TODAY;
Also experienced major extraction issues shooting Federal off-brand 5.56.
Mangled rims, and 15 failures to extract in 100 rounds. Bolt got stuck in chamber multiple times, with fired and unfired rounds. Took lubrication the bolt while partially in battery and strikes onto the charging handle to release. Firearm was lightly greased with Automatenfett prior to shooting.
Had a couple blown out primers too.
Is this a headspacing issue?