Results are in. Here are the barrels

Post-1893 unknown Belgian maker Cast Steel
Non-standard 1002 Very Low Carbon Steel with high Phosphorus & Silicon - 53,000 psi
(This is slightly less than the average of the Pattern Welded samples)

Unknown date of manufacture Pieper Eclipse, likely Cockerill fluid steel
Non-standard AISI 1030 with high Phosphorus & Manganese - 99,500 psi