So I found a pristine Smith and Wesson model 18-3 .22 and based on the serial number it puts it at a 1971 build per a bit of research, but I was wondering if this makes sense that it would have a frame mounted firing pin because there is no firing pin on the hammer. Serial is 1K734XX if it helps. It says they may have switched this exact year from hammer mounted to frame mounted but I trust you guys more than AI.

I recall mine from 1979 or so has the frame mounted firing spring. I think all the RF did.

So does my J frame 650.

Maybe you’re right that they all did, but I was told that they used to be hammer mounted until sometime in 1971.

Every rimfire S&W I've ever seen manufactured after 1920 had a frame mounted firing pin.

OK, good to know, this is why I need to stop consulting AI on anything.

Per SWSC the 18-3 was about 1967 to 1977.
It will have gas ring on yoke if not a very late 18-3.

The SWSC states that your serial would fall into 1971 ranges.

As mentioned rimfire had the frame mounted firing pin pretty much forever, it is center fires that changed from hammer to frame mounted.
I myself won’t own a centerfire without a hammer mounted pin

my only comment, would be to buy a copy of the Standard Catalog of S&W,

I have a couple copies, and they help greatly answering these type of questions,


I am fortunate to know Rick Nahas, so if the book is not forthcoming with whatever I need to know, I ask him

I have a Smith M18-3 with a serial number of 1K95xxx, like yours, a 1971 build, and it has a frame mounted firing pin. Mine was virtually new when I bought it off GB, and I soon found that ejecting empties was neigh near impossible...very tight chambers. Hope yours turns works out for you. Mine's been every bit as accurate off sand bags as my M41 Smith....

I was able to borrow a finishing reamer from a member over on the S&W forum...it was a loaner that floated around among members. I had it for a cpl months and cleaned up my M18 and a pair of Single Sixes that were tight. HTH's Rod