They should be roll stamped Ideal Grade on the left barrel and on the under Side stamped London Steel. If the gun was sent back to the factory for a replacement barrel or for a second set of barrels, one could order a Field Grade barrel for 1/2 the price of a Field Grade gun or around $12.00 in 1920. Field barrels would be marked Armor Steel. The serial numbers should match the receiver if done at the factory. Also check the lug for the forearm spring and see if itís numbered with. ( 1 or 2 ). A Production Records letter may indicate your gun was made with Demarcus barrels and then sent back for Steel later.