there is a 2 digit code on the left side of barrel, that can tell you the month and year it was made. the fine line engraving was done 1997-2001 on the detachable mag bdls
The first letter has to do with the month: B-1,L-2,A-3,C-4,K-5, P-6, O-7, W-8, D-9, E-10, R-11, X-12. SO "K" would be the 5, which is May. when written out it is "BLACKPOWDERX", Then just write numbers 1 thru 12 below each letter.
the second letter has to do with the year.
R-1997
S-1998
T-1999
U-2000
V-2001
so if your barrel is marked "KR", it was made May, 1997
There is an "*" beside T, U, and V in the blue book, it states that they suspended barrel stamping from august 1999 till october 2001, but they did mark it on end of shipping box flap with date code.
all of the abover courtesy of blue book of gun values, 29th edition, p.2127-2128