We all were taught by our dad or grandfather to frequently field-strip, clean, and oil our guns. This is why an 80 year old rifle can have a tight action and pristine bore, despite the fact almost all bluing is worn off from use. Not everyone was taught to care for their rifles in this way.
We frequently get rifles into the shop which are so poorly maintained, it's truly mind blowing. The ejectors are cemented into the receiver with a paste of dirt, rust and oil residue. The bolt lugs are galled at the contact points. The extractor ring will barely rotate on the bolt, and underneath the ring we find it dry and dirty. The barrel channel is packed with pine needles and the barrel is pitted with rust from decades of hunting and never pulling the action out of the stock, etc, etc. When people do this, they can expect "failures", even though it is hardly the fault of the rifle design.
