The model number should be stamped on the barrel just above the trigger guard.
Could be an inspection number.
Yes and it dates the gun at 1939
25-150 USD
Produced in 1973.
THE NUMBER IS A PRODUCTION NUMBER NOT A MODEL NUMBER. I HAVE USED THAT NUMBER TO IDENTIFY PARTICULAR GUNS IN MY COLLECTION BUT, I AM NOT CERTAIN IT CAN BE CALLED A SERIAL NUMBER EITHER.
Depends on whether it is an NFA item or a C&R
Stevens 12ga. /mod dhead naught
model is stamped on gun frame inside cylinder housing
When you release the catch to the cylinder you should see the serial number stamped on the crane at the swivel.
Please re-ask the question and provide the model and guage or type of gun. "Acier Special" means special steel and is stamped on many different models.
If the number is engraved and not stamped then it was done by a previous owner and not Colt. It could mean anything.