Not a lot. I thought we were talking about a locked breech pistol. A straight blowback is a different critter. Most straight/undelayed blowback pistols really only need an extractor in order to pull a misfired round and to guide the case consistently toward the ejector, and when fired will "extract" and eject just fine without an extractor at all. Ejection may be all over the map...but they'll run. They utilize residual gas pressure to blow the case out of the chamber, and a weakened spring lets the breech open with more of that pressure available.
I remember a test once with a .22 auto rifle. Rounds were clocked with and without the action spring. The rounds fired without the spring actually showed slightly higher velocities, along with bulged cases. How that happened is a little mysterious...but that's how it rolled.
