The only one that I ever had problems with was a Scout M1A built with reproduction parts. Four warranty repairs later it still wasn't right, but Smith Enterprise was able to make it reliable. I ended up parting out the Scout.
I replaced the Scout with a 18" rifle custom built by Smith Enterprise. Awesome rifle, and outstanding customer service. Over the years I had Smith Enterprise custom build four additional M14s for me, all of these rifles are outstanding and SEI's customer service has been consistently excellent. This is my 1st hand experience, not some dog-pile thread on some other forum.