The mv letters in the serial number that you provided indicates that your browning c2g model B25 was made in 2005.
1988
The last 2 letters in your serial number NZ indicate that your Browning 325 in 20 gauge was made for browning in the year 1991.
1992
See the Browning website- customer service. Date of prodcution by serial number listing.
A citori 325
The browning 325 grade II was made in 1993,1994.while the citori 325 golden clays were made in 1994 only.
That sn does not follow Browning's convention. Call Browning.
You will have to call Browning to find out.
The 2 letters NZ at the end of your serial number indicates that your Browning 325 shotgun was made in the year 1991.
What is the age of your browning 325 grade 6 serial number 16179NM?
1990.
1994