Why do some people have a preference for the hammer mounted firing pin over the frame mounted firing pin in some S&W revolvers? Example: (629-4 vs. 629-5 series)
Looking for expert opinions.

Myron

Why do some people have a preference for the hammer mounted firing pin over the frame mounted firing pin in some S&W revolvers? Example: (629-4 vs. 629-5 series)
Looking for expert opinions.

Myron

The geometry is better for the frame mounted pins, they can be dry fired with very very little chance of damage even if you dry fire a lot. Hammer mounted firing pins (hammer nose is what they actually call it) will fail with EXTENSIVE dry firing. There may be other reasons as well.

Frame mounted firing pins can be set up to perform with lighter trigger pulls and lighter ignition strokes for competition guns. Beware the short pin!

The frame-mounted firing pin, by it's very design, more closely controls fp movement and is more suited for high pressure cartridges.

Last night I installed extended firing pins from Cylinder and Slide in a half dozen newer N frames. That's right, 4 different Perfomance Center guns received new firing pins because the originals that came with the guns barely stuck out of the frame!

If you hold the firing pins up next to each other, you can barely tell a difference in their length. As soon as you install it and see the extended pin stick out of frame, you won't doubt that the there is an improvement in potential reliability. Now my N frame pins stick out as far as my J and L frame pins.

Can you hear me Smith and Wesson!?! I don't trust the short frame mounted firing pins you insist on installing in all of your new N frames!

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Can you explain why that would be the case? I just don't understand how the hammer mounted FP striking the empty charge hole would damage it.

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Mike
686 no dash

IT IS MY UNDERSTANDING THAT WHEN THEY SWITCH TO MIM HAMMERS THAT THEY WERE NOT ABLE TO PUT THE FIRING PIN ON THE HAMMER ANY MORE.

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I believe it is a metallurical question in that repeated shock subtly changes the metallic crystalline form which leads to microcracking and eventual failure. Kinda like repeatedly bending a paperclip until it too fails.

Que se vaya bien!

BMC

I will try to explain the difference in durability between hammer-mounted strikers and frame-mounted firing pins:

Hammer-mounted strikers' failure modes tend to be chipping on the very tip of the fp, and that is due to the nature of the fp being "wiggly" to allow for manufacturing tolerances between hammer and frame dimensions. These manufacturing tolerances are inevitable, and to keep costs down, the wiggly feature allows the stiker to impact the frame and be guided into the fp bushing, and through the hole. The hammer-mounted stiker design is original to S&W and most other revolvers with a late 19th century design origin. The K22 and kit guns don't use a hammer striker for the simple reason that the soft .22 rimfire case is subject to flowback into the primer hole. The frame-mounted fp prevents that.

The centerfire frame-mounted fp is a much more recent design, having been introduced on the Charter Arms, Colt MkIII and MkIII, Ruger Security Six, and the S&W designs (excluding K22 and Kit guns) of the last ten years or so. It is used exclusively on newer and high pressure revolver designs, notably Freedom Arms, VIrginian Dragoon, Hammerli, S&W 500, etc. The reason frame-mounted fp designs tend to be more durable is because the fp does not have to endure the frame impacts like the hammer strikers. It is through-hardened to withstand both hammer impact and primer thrust. The frame-mounted fp design is more resistant to higher pressures because it is better able to control primer cup flow i.e. closer tolerances for the moving parts. Once a suitable material and heat treat is found, the frame-mounted fp is amazingly durable. Charter Arms made their fp out of beryllium copper, a spaceage alloy formulated for strength and durability.

I have an H&R Model 633 .32 S&W that I bought in 1979 that has a frame mounted firing pin.

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Thanks for all the info!
I was a bit confused after reading a comment in a post on the forum that a particular gun had the firing pin mounted on the hammer "where it belongs".
I figured that it was in some preference to "tradition", rather than practicality. My instincts were confirmed by your answers!

Myron

Because when S&W changed to the frame mounted firing pin on their center fire revolvers, they switched from forged color case hardened triggers and hammers to MIM parts (except on Performance Center Revolvers). Colt put a frame mounted firing pin in the Python and the .357 and that dates back to the mid-1950’s - they work fine. MIM parts function just fine too and are very consistent dimensionally, but they’re no where near as pretty as the old parts. It may be a shallow reason, but it’s a reason.

It’s my understanding that S&W made the change to reduce skilled labor costs necessary to fit the hammer nose (S&W’s name for the hammer mounted firing pin) and its bushing. The hammer swings an arc and the hammer nose needs to pivot so it can pass straight thru the hole. On some models the hammer nose is spring loaded in the down position. The frame mounted firing pin design is easier to manufacture and assemble.

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John Traveler and S&W Chad both gave good answers.

I would add that a hammer mounted firing pin is better for use with guns that have a very light action job, because they deliver a heavier blow. The frame mounted pin, as already pointed out, is better suited to primer flow control issues.

What did the firing pin say to the hammer?

"I've been framed!"

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NRA Life Member

My understanding is the frame mounted alleviates the liability concerns of the former design and better allows MIM design use. I am of the mind that the older hammer mounted pin allows for a more refined trigger pull. In other words, despite the protest of the current SW regime, the newer design is primarily a cost savings and liability sparing change.

You did miss the Colt Python in your listing!
About 1955 or so.
But it was caught by S&WChad, my bad?

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Wherever my mind isn't
Jim