Hello All, I recently became an LC junkie and happened on a 1918 FW Ideal grade 12 ga. for $150 that needs some tlc. I do not own a bore gage but under the right barrel, where the slpinter is, it is marked C 4 4 London steel. On the left barrell is marked, C London Steel. Do the letters C mean that it is cylynder bore? What does the two fours mean?