I’ve run about six Fullfield models on guns up to a light .50 inline with nary a bobble. Can’t speak to the Chicom models. Fullfield 2, E1, and Droptines are made on U.S. machinery in the Philippines. Haven’t tried the Droptines personally, but have seen multiple positive comments here.
All my Burris scopes have adjusted as marked so far, even an old fixed 6 I just got, unlike single bias-spring models from You-Know-Who.
