As a result of Mr. Hackett's post I reread my first post and find that I made a wrong assumption in the first sentence. It should properly read that 1535 guns were shipped to Rochester Armory with unknown markings. The quantity is justified by Jim Stubbendieck's research of the records as reported in his book about production records on pages 114 and 115, but we only know about very few of the markings on these guns as reported by the membership. The point of this thread is to try and obtain a better understanding of how the guns were marked which might lead us to explaining the USA-F marking.