Flashman,
The failure to eject or cock the hammer suggests underfunction. That is, there's not enough energy from the spent round to function the action. Likewise, there could be something mechanically wrong which prevents the normal operation of the firearm. Here are some suggestions:
What brand of ammo and have you tried different brands? Sometimes guns can be ammo sensitive. Guns, like their owners, develop allergies too. Switch ammo and try different types to see if it still malfunctions.
For testing purposes, use only a factory magazine. Aftermarket magazines with non-metal or non-spec feed lips may be causing the malfunctions.
How clean is the firearm? My friend's 10/22 wouldn't feed without locking up. Turns out he never cleaned it for over five years of regular shooting. All that fouling finally affected the function. We laughed over about his griping and stupid us, should have told him it was broken and offered him $50 bucks for it b/c we're his buds! Make sure that chamber is clean.
Check the straightness of the recoil spring guide rod. If it's tweaked, it could slow down the motion of the bolt such that it'll jam.
Have a gunsmith check the chamber with a go and no-go gauge. The chamber may also need a little polishing if the tolerances are so tight that a bit of dirt from 3 rounds induces a jam.
That's all the suggestions which my sun-soaked brain can presently spew out. May come back with more later.
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