This is a MG34 movie prop.  It was used in the TV series "Combat" with Vic Morrow.

They had several of these and they were used when they wanted to blow a machine

gun out of a foxhole.  When the series was cancelled, the production company held

an auction for all the props, etc.and this was purchased at that auction.  It is made of

molded red rubber and painted black.  It is somewhat flexible.