Some of those chips (perhaps all) were likely made by the USPC Co. before 1947.

After getting the USPC Co. equipment, I am guessing that Burt made die cut chips very similar to the chips that the USPC Co had made for many years. In some cases, it may be impossible to know who made them.

My impression (mainly from the articles published by Robert Denbrow in the club magazine in 2019) is that the Burt Co. before 1946 mainly made serrated edge plastic chips (similar to what can be found in drug stores today), and clay chips (called "Smoothies"), which usually had rounded edges. Burt specialized in metal die cuts, but Denbrow does show a few early Burt die cut chips with white plastic inlays that are hard to distinguish from USPC chips.