Before removable bushings were used, each shot payload and powder charge had different bars; Good in that you never had to worry about anything once you found one you liked. Bad in that there was no other way to experiment with loads except buying a whole new bar. Note the price: $3.50.
I'll use the top one in the first of 243winxb's pics as an example:
Bar # Dram Eq. Shot load Powder charge (gr.) Powder type Hull length Wad
OH 2/34 1 1/8 oz. 22.8 Win. 473AA 2 3/4" Plastic unit (Usually WAA-12) If there were a number here, it would be fiber wad height in inches.
That was a trip down memory lane!