powder_monkey,
Your Huntsman 12 Ga with a serial number prefix of "AL" was manufactured in 1972 and was the first year they were offered for sale. The barrel should have a screw-in breech plug with 2 holes for a spanner tool on the rear face.
I don't know what other information you are looking for about your Huntsman. Perhaps you can elaborate.
Sprint
EDIT!!
Sorry, I just realized I gave you the wrong information above. Your Huntsman was manufactured in 1973 and probably had a knock-out breech plug. Truly sorry for the error.
Sprint