Those Schwinn serial charts are good considering the loss of records,re-use of numbers, etc. But they are far from complete. I have had at least 3 Schwinns I could not place in the charts. There are instances where the last number of one day and first number of the following day don't coincide, and at times leave huge gaps between them. Plus the stamping isn't always terribly deep, and over time letters and numbers resemble others. If you use the Angelfire chart, check out 1949, 7/14 F146384-F145902 obviously a typo, but it's the type of mistake that could cause confusion because the day before ends F145383, so if you're scanning through, you could be led to believe that 1000 numbers were skipped