I bought an UPUR-1LH for my SBR build and let it sit in the "to be built" bin. Well, I saw a post about a sticky bolt, and thought I'd double check my upper. Unfortunately, I had a sticky bolt. Well, I called CMT last week to explain the problem. All I they asked me to do is send them a pic I took, and a email to remind them of the conversation. 30 minutes later, I get an email with a tracking number. Today I got the upper, and the bolt works smoothly. Return postage is in the box, and we are good to go!