I have 2 1917 extractors that do not have the gas vent hole drilled in the tip. Both of these extractors have the letters "CV" stamped on the underside, indicating they are chrome vanadium steel. Perhaps the CV marked extractors were made under contract during WW II to rebuild 1917's. Maybe the experts will know.

You should be able to determine if you have brass remaining in the throat of your rifle by inserting a long, narrow screw driver or cleaning rod minus the tip into the chamber. The tool should catch the edge of any brass and produce an audible click. Check out the Youtube videos for HOW-TO's on broken shell extraction.