This won't be much help, but I went through the book, "Gunmarks", by David Byron, and there was no such mark listed. Nor was there any similar mark. The book was published in 1979 so there may be newer info out there. There was no such mark in my Remington sources, but others here are more knowledgeable than me and may be able to help. At least you now know that the common sources don't show the mark. It may be some kind of company ownership stamp.
Dan