First thing comes to mind is a weak or broken extractor spring, or possibly a broken or bent extractor. Either might let the spent round leave the bolt face before it hits the ejector. High velocity rounds might push the bolt back faster causing the higher likelihood of separation. The empty has enough momentum to clear the chamber but isn’t ejected out of the receiver when the bolt comes back forward.
A repair could be as simple as removing the bolt and soak in lacquer thinner to free up the spring. It seems to dissolve hidden gunk better than anything else I use. While it’s out give the extractor a visual inspection. Slide a cartridge in and out of the extractor to get a feel for whether it’s grabbing the rim well enough. If confident enough to disassemble the extractor you can just replace the spring. Can’t hurt to freshen an old spring like that.
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