Hmmmm
I have no experience with the 7.65 Argentine in the Brownings, but I am not aware that there is any difference in the extractor or the cams for that caliber. I don't recall what caliber lobo shoots his 1928 semi in. Might be -06 and it might be 8mm, but I think he has said that it has 1919 internals. Are you using the 1928 internals or 1919? You might want to call OOW next week for their input, but I'd be surprised if there is a different cam. I have a 1928 LSP and bottom plate. The extractor cam looks just like early 1917 ones I have on Westinghouse LSPs, with the little "hook" on the inside edge. Same on early 1919s. On (what I think are) later production 1919s, the front cam has a re shaped lug that is flat on the rear facing surface, with no hook. I'll get one of my Westinghouse plates out to compare side by side. Maybe I am missing something.
By the way, I assume we are both talking about the front cam with the right angle lug, not the extractor FEED cam which is the flat, rear one.