Going to have to write this down before it gets lost in the clutter of my head. IF anyone spots an error, or has some additional information, feel free to post updates.
Using Roman Numerials, starting with 1954 as 'X'.
X = 1954
XI = 1955
XII = 1956
XIII = 1957
XIV = 1958
XV = 1959
XVI = 1960
XVII = 1961
XVIII= 1962
XIX = 1963
XX = 1964
...continues without skipping until
XXVI = 1970
Then, for some reason not really explained, they switched to:
XX7 = 1971
XX8 = 1972
XX9 = 1973
Then back to:
XXX = 1974
Then it chages to a letter code. Should be simple, but they skipped various letters throughout the "A" code, then decided to skip OTHER letters through out the "B" code. Didn't want to make it too easy I guess.
AA=1975
AB=1976
AC=1977
AD=1978
AE=1979
AF=1980
AH=1981 (notice they skip AG)
AI=1982
AL=1983 (skipped AJ and AK)
AM=1984
AN=1985
AP=1986 (skipping AO)
AS=1987 (skiping AQ and AR)
AT=1988
AU=1989
AZ=1990 (skipping AV,AW,AX, and AY)
BA=1991
BB=1992
BC=1993
BD=1994
BF=1995 (skipping BE)
BH=1996 (skipping BG)
BI=1997
BL=1998 (skipping BJ and BK)
BM=1999
BN=2000
BP=2001 (skipping BO)
BS=2002
BT=2003
BU=2004
Do not know how the letter code continues...or why they selected the letters to skip.
There will be proof marks (usually two). One of them will be a PN marking...this is a black powder proof. Have had people show that to me and claim that their gun is nitro proofed (thinking PN is for Proof Nitro)..it is not...that's a black powder proof.
Will USUALLY be a maker's stamp...but not always. In the early years, was common to have whoever improrted the gun supply whatever stamps they wanted..Navy Arms, Replica Arms, Sile, CVA, etc. But it all boils doen to a few makers. Common ones are: (aside from writting the company name out):
Pedersoli usually uses "DAP" or "dp".
Uberti usualy uses a "U" surroumded by an octogon outline...the octogon to represent a barrel outline.
Pietta Usually uses a "FAP" in a horizontal diamond outline.
Palmetto (who made a lot of Dixie Gun Works reproductions) uses a palm tree in a circle.
Armi San Paolo uses a DGG..this is also found on EuroArms (as they are more or less the same maker now). Often hard to figure out as they overlap the DGG.
Armi Sport will usually use a "AC" in a circle.
How Beretta will or has changed this I do not know, but they do seem to be buying up or joining a lot of BP production.
The Colt first and second generation guns were made in Italy as well...but only as rough parts, the fix and finish by Colt, so only Colt's marking are on the guns.
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Just wanted to get this on-site so I can stop hunting up the written copy whenever it comes up as a question on-line.