  The structure of the reduction of an admissible $G$-covering $Y \to X$ at
primes $p$ dividing $|G|$ is investigated. Assume $|G|$ is not divisible by
$p^2$ and the $p$-Sylow group is normal. Following Raynaud it is shown that
there is a group scheme $\cG$ over the smooth locus of $X$ for which $Y$ is
still a principal bundle away from the special points. A structure at the nodes
involving Artin twisted curves is discussed.
