Disclaimer: I have been involved in aerospace manufacturing for almost 30 years and am an FAA licensed mechanic and pilot. Loving my MK-9, I purchased an M1 Carbine from Kahr's sister company Auto Ordinance a few years ago. This was a fun gun to shoot, but I never could get it to zero. After a year of drifting the rear sight back and forth, I finally put an adjustable rear sight on it. Still no luck with zeroing. At a local HP reduced match last weekend, the range master told me to check and see if the barrel was tight in the reciever. I though he was kidding. Just a few minutes ago I unscrewed the barrel from the receiver with light finger pressure. Not good. No Kahr customer service for me this time around. I am going to rebuild the entire rifle myself using red locktite.