There should be a light film of oil between moving parts such as the slide rails. Not a lot, just a few drops. Don't soak it in oil, and don't run it dry...common sense amount, as they say. To much, or not enough lube would have no bearing on "bullets jamming into the barrel". Are you saying fired bullets are firing, but sticking in the barrel? Are loaded, unfired rounds sticking in the chamber? Those are reloading related issues. If your rounds are loaded way to long, the lead bullets could be sticking against the rifling, causing the bullets to pull free from the case, dumping raw powder when you eject the unfired round.
If you made no changes other then "lubing" the gun, then you must be soaking it in oil. just A FEW DROPS on major metal to metal surfaces, like the slide rails. Use a gun type lubricant, not motor oil, or whatever..
Larry