I think you may have left something out on your question. What does ? signify? Which manufacturer produced your gun, Walther, Mauser?
What proof marks are on the gun?
Instead of using long serial numbers they started with an "A" suffix, when 9999A was reached the numbers start over with a "B" suffix. At times a 5 number serial was used along with the letter suffix. More important to the value is the code used on the gun such as "ac", "ac40" thru "ac45" and "480". If your gun is an "ac42" there are 2 variations. The first has an eagle over 359 on all parts and is valued higher than an "ac42" without them.
The values are: 90%-$775, 80%-$650, 70%-$525, 60%-$425
Add 25% for the first variation.
These are private party values.
I hope this helps you,