A citori 325
What is the age of your browning 325 grade 6 serial number 16179NM?
The 2 letters NZ at the end of your serial number indicates that your Browning 325 shotgun was made in the year 1991.
That sn does not follow Browning's convention. Call Browning.
The browning 325 grade II was made in 1993,1994.while the citori 325 golden clays were made in 1994 only.
1990.
1993
1991
It was made in 1989
The 2 letters in your serial number(NR) indicate that your Browning 325 grade VI was made in the year 1997.
You will have to call Browning to find out.
Your question cannot be answered without you providing the full serial number to your browning.