Well, you made me go dig in my library. You're right, but so am I. The Thompson Blish lock .30 cal rifle was submited for trial in 1920 (or so) at the same time as Garand submitted a primer actuated design. Neither worked out but Garands was promising enough that he was retained by the government for further designs, one resulting in the M1.
FWIW there is a picture of the Thompson rifle in W.H.B. Smith's "Small Arms of the World". It is on page 85 of the 10th Edition.
Last edited by deadin; 10-29-2011 at 11:54 PM..