No... A single letter prefix N would mean it was made in 1953, frames that are of current H&R production have two letters preceding the numbers, if you read the instructions on the accessory barrel page, it says the frame must have been made since 1987(NB or HB), anything made since 1986 has a 2 letter prefix, the first being N(NEF) or H(H&R), the second letter is the letter that denotes year of mfr as far as barrel fitting is concerned, as in HN123456. The old H&R production only had one letter in the serial number as shown in the FAQs, as in N123456.
Further more, H&R won't fit and of the asterisk * marked barrels to frames made before
19992000, those would be HP or NP.
Tim
Additional barrels may be added to firearms of our manufacture since 1987 only, with a serial number that begins with N or H. We do not install additional barrels on any other manufacturer’s firearms.
http://hr1871.com/Support/accessoryProgram.aspxSecond letter of prefixA= 1986
B= 1987
C= 1988
D= 1989
E= 1990
F= 1991
G= 1992
H= 1993
I= 1994
J= 1995
k= 1996
L=1997
M=1998
N=1999
P=2000
R=2001
S=2002
T=2003
U=2004
V=2005
W=2006
X=2007
Y=2008
Z=2009