You have the two solutions right there. I take the barrel out of the stock, take the barrel and trigger assembly outside, and with some brake cleaner, spray the inside of that trigger out real good. Then shake that barrel and trigger to try and work out all the brake cleaner you can. After that I hit it with an air compressor and finally, a very light amount of oil into it. When that back safety gets gummy, it it will slow the bolt down.

Also like mentioned, that back screw by the trigger guard, if you drive it in too far, it can pinch something up there. I never crank them screws into the locking lugs.

I did have the trigger gum up on me, and it did stop the rifle from going off. They just gather a lot of crud.