Alaskan on a M1 D

I friend of mine put together a M1D from parts. He put a Alaskan on it. the scope had a post instead of crosshairs. The scope did not have a prefix. the serial number is # 12085 can anyone here tell me from the serial # the year the scope was produced

Right after WWII, maybe 1946-47. Lyman restarted commercial production with serials where they left off before the 1944 military contracts, in the low 5000's. Hard to tell how many they sold and when they reached the 12,000 range.