I just sent an upper back to them. The striker was sticking. They built it with their parts. They were very apologetic and wanted to male it right. I should have it back this week. I couldn't get one mag through it with out a FTE or stove pipe. The trigger was not resetting all the time either. I was not the lower since a factory upper functioned perfectly. So I will Gove them the benefit of the doubt and wait and see.