When it doesn't fire is there a click? If no click then the two things I thought of is the action is not fully cycling or the hammer is not staying locked and is instead following the bolt forward. When you cleaned it did you lube it when done or leave it dry? Metal rubbing on metal needs lube. If you hear a click when you try to shoot then its other things.
Times are tough - Keep your powder dry
"These are the times that try men's souls." - Thomas Paine