Chris, There is no doubt that S'G' went back and used serial numbers off of bad IP receivers but these seem to show up about July/August 1943 judging by the barrel dates I have seen. I am sure that S'G' had new stamps made ASAP including the receiver stamp. The known IP marked receivers span from 1.76 to 1.87 range and if only a third were made that would be over 30K and plus the ones in the 3.2 range that are IP marked. But Doerfner did not have the time to wait for S'G' marked receivers as he was being pressured by the Army to start producing or else. But looking at how many IP stamp receivers have been showing up just at CMPauctions it would seem that the 30K+ to 38K figures in some publications for IP made receivers might be pretty close to the amount made and used by S'G'. But I would ask if S'G' were to get receivers from S.G.,wouldn't they be marked as the Inlands were on the left side with an S.G. stamp?