I have the SDN6 and have had to send it back to replace the ratcheting part. It wore smooth and would walk off of the muzzle device. I was skeptical to send it back to AAC, since I had heard that their customer service have gotten bad after the company sold. Well, I called them and they emailed me a shipping label and scheduled for UPS to pick it up at my house the next day. I sent back to AAC for the warranty repair. And surprise to me, I received it back seven days later. It had been refinished and fixed. I only have positive things to say about their customer service.
