Ruger C.S.
I don't know about other firearms, but I will give my plug to Ruger's Customer Service. I bought a 10/22 in the late 1970s. Mine never fed reliably, in spite of the fact that many of my friends with identical stock rifles worked flawlessly. I tried many different types of magazines from Ruger and other after-market brands, lots of different types of ammo, but it never worked reliably. I put it in the closet until the early 2000s when an acquaintence suggested that I send it back to Ruger. I contacted them, sent them the rifle and one magazine along with a letter explaining my situation. They sent the rifle back to me within a few weeks with my one magazine plus 2 new magazines. Since that time, it has worked flawlessly. I presume they polished the feed ramp, receiver, bolt and/or other parts. I'm not sure what they did, but was very pleasantly surprised that they stood behind their product and corrected the problem decades later at no cost. If you don't ask, then the answer is always "no". Good luck with your firearm.