S&W M18 Serial number formats

[wileybelch]

I have seen M18 (Combat Masterpiece) serial numbers in several formats. Many are 6-digit preceded by the letter 'K', others have numbers before and after the letter 'K'. Is there any significance to the difference? Also, what is the meaning of the dash form of model numbers? I've seen model numbers as 'high' as 18-7? Can anyone help here?

 

[mrray13]

I can't help with the serial number format, but can shed some light on the dash. Although dates of manufacture can be represented by different serial number formats.

Each dash represents a significant change to that particular model. Meaning a no dash 18 is pretty much the original design, while a 18-7 represents a gun that has seen 7 different revisions. Examples of revisions could be dropping of the barrel pin, no recessed cylinder vs recessed, all models now round butt vs a choice, etc.

That's fairly generalized, someone will come along and be able to get more specific.

 

[highpower3006]

The earliest post war adjustable sighted K frames had serial numbers starting with "K". When they ran out of of numbers at K999999, they started adding a number prefix. Around the early1980's or so (I'm not real sure of the date) they changed their numbering system again to a three letter prefix with a series of numbers following.

Early K and N frames had only a series of numbers, many times S&W started over with number 1 when they switched frame sizes. For instance all N frame guns started at number one even though they started production after K frame guns that also started at number 1. To make it a little more confusing, there were K frame revolvers with a "S" prefix and N frame guns with a "S" prefix also.

Here is a 1901 first model target:

1948 K22 Masterpiece:

1976 Model 66

1982 M66-2

I don't have any Smiths that are newer than the early eighties, so I don't have a picture to illustrate the later three letter prefix.

As was mentioned, the dash number represents a engineering change. Some changes in dash numbers represent internal changes only, while some will signify major visual differences. For instance, most N frame revolvers up through the -2 guns will have pinned barrels and if they are magnums, they will have recessed cylinders. With the -3 engineering change the pinned barrels were eliminated and the recessed cylinders were dropped.

BUT, that does not apply to K frame revolvers as there were so many changes over the years that the dash number can be quite high before the pinned barrels were eliminated.

 

[FlyFish]

S&W used the "K" serial number series for K-frame adjustable sight revolvers beginning in 1946, with SN K101, reaching K999999 in 1970. Rather than continue to an 8-character (K plus 7 digits) SN in the same series, they elected to keep a maximum 7-character SN and moved the position of the "K" - so the next number in the same series became "1K1", continuing to "2K" and so forth up to 9K99999 in 1976, at which point they continued with 10K0001, eventually ending at 311K273 in 1983 when the current 3 alpha plus 4 numeric system was adopted.

 

[carguychris]

Examples of revisions could be... no recessed cylinder vs recessed...

I realize that you were probably just citing arbitrary examples, but FWIW all rimfire Smith revolvers made after sometime in 1935 have recessed (or counterbored) cylinders, up to and including today's production. This is done to contain case head failures with soft rimfire brass. The recessed cylinders were only phased out for K and N frame centerfire Magnums circa 1982-83. (L frames have never had recessed cylinders, and this change substantially predates .357 Magnum J frames.)

I'm just trying to eliminate potential confusion.

...eventually ending at 311K273 in 1983 when the current 3 alpha plus 4 numeric system was adopted.

This is correct, and just FWIW, there is generally no readily discernible way to differentiate any particular revolver model under the current 3-letter 4-number system. Most standard-production revolvers have been lumped into the same big pot, so to speak, which started with AAA0001 and AFAIK has recently reached "E".

Some special runs have gotten special serial number prefixes (e.g. KSP prefixes for the KY State Police), and some models have been assigned to certain ranges (e.g. early M&P's started at MPA and ran through at least MRN), but I don't believe there's any particular way to identify a newer Model 18 under the system.

 

[wileybelch]

Thank you, Flyfish, your reply explains all the SNs I've seen.

 

[Sevens]

Just wish to throw in my two cents about the dash numbers and the WEE little bit of insanity that goes along with Smith & Wesson's use of them...

I have a Model 17-6 with a standard target barrel, manufactured in 1988. Don't know how many dash-6 variants out there have the standard 6-inch target barrel... and how many of the dash-6 guns instead have the MASSIVE full-lug barrel that the Model 17 morphed to, never to return to it's classic roots.

That's right... some were standard target barrels, some were the gigundo full-lug barrels, both of which wear the dash-6 badge.

IMHO, you simply cannot make much l-a-r-g-e-r of a change in one model of revolver. How on Earth that S&W decided it didn't earn an official mark of an "engineering change" will forever be lost on this S&W fan.

 

[James K]

Originally, most gun makers used a separate number series for each model. Of course, that led not only to duplicate serial numbers, but also meant that anyone attempting to trace a gun had to know the model, which was often not marked on the gun. Then, under the Gun Control Act of 1968, then-ATTD (now BATFE) mandated that serial numbers had to be unique within a manufacturer's production. That led to some of the S&W changes and also to numbering like that used by Ruger, which has a prefix indicating the model.

Then some wisea** at S&W figured that with modern computer horsepower, any serial number could be put on any gun and didn't need to connect to a model number at all. So ABC1234 could be a Model 36 and ABC1235 could be a 686 and no one cared. So if there is a need to trace a gun, all that is needed is the serial number, not the model, caliber, finish, or anything else about it.

Jim

 

[Sevens]

Awwwww, JIM!

I saw that you had posted in this thread and hoped that you'd have an answer or apology for my wacky Model 17-6.

Not that my gun is wacky. Just that S&W is wacky. And you come up with some of the best answers for that.