I bought a 9mm upper assembly which took several weeks to arrive and when it did show up they sent the wrong muzzle device. I needed a 1/2-36 and they sent a 5/8 24. I sent them numerous emails stating the problem. They don't respond and I tried several phone calls but they don't answer the phone either. It's been several months and have gotten nowhere with them. I'm writing off the loss and will do everything I can to steer people away from them. I even sent an email to Delta trying to get some service. No good with them either. I ordered a upper assembly from Bear Creek since my disaster with Davidson and was very pleased.