I estimate that there are about 400 large proofs of the Fourth Bureau Issue (FBI) of ordinary stamps that got out of the U.S. Government and stayed in the public domain. This includes 13 sets of die proofs, nine signed by Postmaster Generals, as well as other unsigned die proofs, trial color proofs, and die essays. Most of these proofs were either gifts from a Postmaster General (PMG) or became the property of engravers who worked at the Bureau of Engraving and Printing. Many of the proofs still exist, although some of their proof cards are trimmed down from the normal 6 in. x 8 in. format. This frequently removed the control number on the reverse of the card. Counterfeit 5 digit control numbers were added to some of these cards. The proofs in the die proof sets were pulled in 1922-26 (7 digit control numbers), 1929 (6 digit control numbers starting with a 1), and 1933 (6 digit control numbers starting with a 3). I believe that 9 or 10 of the die proof sets contained only pre-1929 proofs. Only a few of the original sets are intact today. The die proof colors reflect the colors of the FBI stamps from the corresponding periods. Shown below are PMG signed 1922 and 1929 11-cent Hayes die proofs. All 1929 signed proofs were backdated to their original proof dates. Also shown are a variety of colors found on the Hayes die proofs. I would like to hear from other collectors of FBI proofs.