Wouldn't be a cause for any concern in a Ross MkIII. People have filled the barrels with pebbles and sand, filled a case with pistol powder and still not blown one up.

This Sgt. Carey was apparently taking no chances with soft catridge cases sticking in the chamber and "emptied his oil bottle into the breach" before a rapid fire incident.

Oiled cases have little or no cylinder wall adhesion, enormously increasing thrust on the bolt. With normal case adhesion there is very little backwards thrust on the bolt, according to experiments done at RSAF Enfield.