Here's the answer on the barrel steel.
TO: Green Mountain Barrel Company
Greetings from the hot & humid South.
Can you tell me what steel is used in manufacture of the .40 caliber 13/16" Black Powder Rifle Barrel?
Van Lopez
River Ridge, LA
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REPLY: Hi Van,
Thank you for contacting Green Mountain Rifle Barrel. The 134036 and 134042 products are made from 1137 steel.
Thank you for your inquiry.
Michael Hagar
Distributer/Dealer/Retail Sales
Green Mountain Rifle Barrel Co.
Here's a comparison of 12L14 vs. 1137.