View Full Version : How To Remove Firing Pin Frame Mounted S&W Revolver

September 28, 2006, 07:58 PM
I have this 940 No-Dash S&W that I just aquired & the back side of the Firing pin comes out from the rear with the sideplate removed, In front of the hammer, This revolver has the cross pin which I have removed but still couldn't get the FP holder/recoil plate to remove, I know the FP is broken in two but can't find any info on how to remove this type of firing pin or even a decent diagram that shows what's involved, I looked at the universal diagram available on Numbrich & I assume that it's closer to the rimfire type that the diagram shows..
I have the FP + Spring coming from S&W..
Somebody here has probobly done this repair in the past, If you have HELP a Brother Out!
How Do You Remove That Recoil Plate after removing the cross pin?
Thanks in Advance!!
S&Ws 442-2, 940, Pre 40 Centennials

September 28, 2006, 08:49 PM
I worked on one here while back and I seem to remember that all I had to do was remove the cross pin and then I pulled the firing pin and spring straight back. I would open the cylinder up and take a paperclip or something very a safety pin and see if you can push from the front and get yours to break free, it may just be getting caught somehow.

September 29, 2006, 06:41 AM
I installed a long thin tape coated brass punch down the barrel & rapped lightly with a shot hammer & it wouldn't move, I will try coming in from the side threw the pins hole with a paperclip, It's possible that the spring is somehow holding it or were the pin broke off it's rough & that's holding things up.. Oh & BTW This is a 9mm Revolver & the endd shake screw was replaced by previose owner witha homemade screw, I assume it fell out while shooting, These need blue loctite..
Hope the Parts get here today from Springfield Mass, That'll give me an idea of what it looks like..

September 29, 2006, 08:20 AM
If it has a firing pin bushing it is driven out from the back of the pistol to the muzzle with a punch after you drive out the cross pin.With the sideplate off and all the internal parts removed. Select a punch that just fits into the back side of the firing pin hole where the pistols hammer hits the pin. With the right size punch inserted into the hole gently tap punch with a small hammer. The firing pin bushing will come out the front of the recoil shield.

September 29, 2006, 07:09 PM
Well I got it apart!!
There was a firing pin bushing in front of the pin. after removing the indexing pin, I put the hammer & it's spring back in & pulled the trigger several times & the bushing started to move, after it bottomed out I made a longer pin out of a stainless taper pin then turned it down to within a few thousands of the original pins diameter, I then installed it to completely remove the bushing with several more dry fires, On a normal exposed hammer revolver this would have been easy but on the Centennial it wasn't.. You can't drive a punch in there. See Pic..
I should have the new Firing Pin & Spring by Saturday or Monday..Waiting..
Glad to have it apart, I won't be sending it to S&W...
Here's a few pics I took of the Frame, Broken Firing Pin & it's Bushing..
Thanks To Everyone!!
940 S&W Apart
Broken Firing Pin
Firing Pin Bushing

James K
October 1, 2006, 08:38 PM
One reason for the confusion here is that S&W has changed the design of that frame mounted firing pin. In the new design, there is no firing pin bushing. The firing pin comes out to the rear and is held by a slip fit pin that is just pulled out when the side plate is removed. A lot simpler and less costly to make.

It is obvious that some folks were thinking of the new design and some of the old. I am glad you got the firing pin out, and good luck with getting the gun fixed.


October 1, 2006, 09:15 PM
Thanks for the information about the change in firing pin design. Although I've never had to change a frame-mounted firing pin, I've always wanted to know how. Until now I haven't been able to get my mind around the conflicting things I have read on the various forums. You fixed that for me.

October 1, 2006, 10:19 PM
Thanks Guys!!
I'm hopeing to get the parts from S&W any day, I ordered them Tuesday & should have already had them...
I made up a tool to go down the barrel with a flat brass base to press the bushing back in, I coated the tool with a few layers of blue tape & then wrapped it with some rubber clear tape so it won't/can't damage the rifling, I made it long enough to use it in a 3"-4" barrel just in case I need it again..
Hopefully reassembly won't be a problem, I'll go slowly as the spring & pin could get missconstrewed with the rapping of the hammer.. Also I can see that getting the pin notch level with the top of the gun will be needed to get the pin to go back threw..
I'll take a few pics as I reassemble the Revolver but don't think I'll run into any trouble..
I also forgot that I believe that the broken Pin was caused by the homemade endshake screw that the previous owner had made, The crane would move forward .005"-.010" extra letting the FP bottom out in the bushing,The cylinder would almost rub the forcing cone, But dry firing would let the FP bottom out in the bushing too? This revolver is Buttery smooth so it's probobly been dryfired a few million times as well.. It also had cut springs on the hammer & rebound that I'm gonna replace with factory or Wolff springs I already have from my other J Frames..
I've also read at the S&W forum that some 940s suffer from sticking cases in the cylinders that can usually be cured by polishing the chambers & using Zero lube in the holes, BTW I have a Ruger SP101 9mm that has never had any trouble & gets shot quite alot..
Bonus is the 50+ TK Moonclips I have for my SP101 will work in the 940, It didn't come with any, I have a package of OE Factory clips coming with my parts order as well..
Here's Hopeing this will be the only frame mounted Firing Pin I'll ever change.
Wish Me Luck!!
Jr. Gunsmith Gary/B92

October 3, 2006, 07:07 AM
S&W has yet to deliver my parts
Tried calling all day yesterday without success

October 4, 2006, 04:21 AM
Please S&W Please Send me ALL My Parts

Great Forum Here!!

October 4, 2006, 09:01 PM
I called S&W This morning @ 9:00am & got right threw
I asked the Rep were my parts were & he replied those were allowcated & should be pulled today, If you don't get them by Friday Call us back..
Allowcated? Does this mean your gonna send them to me?
8 Days & they haven't even pulled the parts yet to see if there in stock
Man this is starting to turn me against them & I love my S&Ws
Had To Rant!!!! :barf:
Here's a Pic of the 940 with a set of Factory S&W Ajax Grips

October 5, 2006, 12:53 AM
Hey man slow down a little. They most likely gave yours to someone else and they aren't in a big rush like you are because their guns ain't broke. These folks are not the usual parts houses that get it right out to you if you know what I mean. It sucks for sure, but give em til next week by Weds, before you get too worried.

The guy that taught me a lot about 45's used to have a saying, " you brought that to me when, oh man I am still working on last years guns, it will get done when I get to it." Most of the time he was picking, but there were times he was more than 6 months behind on his delivery because he took in so many guns.

October 5, 2006, 07:01 AM
I'm Not Holding My Breath!!
Hope my Order Comes Soon, Complete!! With No Backorders.......

October 5, 2006, 07:41 AM
I would tried Brownells factory gun parts first. If they didn't have it I would have tried another source I have for S&W parts. The factory being the last resort. A gunsmith friend of mine has had parts on order from Remington for three months. I asked him if he had checked with Brownells and he said no. He called them and had the parts in the time it took them to ship. The parts cost more than from the factory in most cases which is why he doesn't buy parts from Brownells.

James K
October 5, 2006, 10:01 PM
Yep, there are parts places that take a couple of weeks to ship, and gunsmiths working on last year's stuff, but there are also guys like the customer who brought in his rifle the day before opening day and wanted it fixed RIGHT NOW!! We asked him when it broke. You guessed it - the last day of deer season last year.


October 5, 2006, 10:54 PM
Those come in al the time. The best one I have had was a guy was going on a trip. He brought his gun to me to sight it in for him because he didn;t have time. He had planned the trip for a year, was going elk hunting and had no time to get in shape much less make sure his gun was sighted in. I told him I charged $75 to do the job, believe it or not he paid me to do it. Man o'man Just goes to show that some guys have more money than they need and some need a lot more patience.

October 9, 2006, 10:26 AM
Thanks Guys!!
I am still waiting for the parts, Todays Columbus Day so I know there not going to come today!! Maybe if they used UPS?
I may try to Call S&W but I assume there not open either..
I will finish this post with a few pics of me reinstalling the NEW Firing Pin & spring plus a shot of the tool I made to press/hammer the bushing back in..
I'm hopeing I'll get it back together by this weekend..
The Knob Creek Machine Gun Shoot & Worlds Largest Military Gun Show is this Fri, Sat & Sun, Will Probobly be too busy to get around to shooting it anyway.. This Gun Show Rules!! The Best Ever! & Right in my Back Yard, A few miles away.. Sore Feet Beware!! :D

October 10, 2006, 11:11 AM
Well I final got my parts package from S&W Today!!
They sent the wrong firing pin..
I have contacted them and they believe they sent the wrong part # but aren't sure..
They sent me the newer style of Firing Pin
I emailed them this pic of my broken bushing next to the one they sent #21297
Hope to get the right one soon

October 10, 2006, 04:44 PM
Well I called S&W Customer Service again & got another Rep, The Other must have been to lunch as I asked for him by name, And told him of my delima, He said that the armourer next to him stated that the firing pin hasn't changed in 30 years on a J frame, I know this is bologna because there's been a change & that I have three different Centennials & they all have different firing pins.. The one they sent me the stainless one in the pics would fit my newer 442-2 with MIM parts..
The operator also told me he couldn't physicaly go get a firing pin & compair it to my pics??, Then put me on hold, when he returned he said that his found another part # and would send me both part #s FREE of charge 2nd Day Air..Being that maybe the other was mismarked/mislabeled
I sure hope I get the right one soon..
Come On S&W Help A Guy Out!!
There's a gunshow this Weekend!!
I want to test it & start carryin it!!
My Airweight & Lemon Sqeezer are gonna get Jelouse if Everything works out,It's Gotta Be 100% For It To Become a carry piece..
Range Report Due a few hundred rounds should tell, Wonder if the 940 No Dash can handle +P & +P+ 9mms??

October 14, 2006, 06:00 AM
Well Here we are Three Weeks later
After geting a new end shake screw, Firing Pin Return Spring & WRONG FIRING PIN from S&W, I had to reorder the FP again..
This time I talked to two different Customer Service Reps, One of them found the right diagram & sent me FREE of charge a Firing Pin, firing Pin Bushing & Retaining Pin + another of the other type of FP,Just in case one was missmarked, I now have two of them If I ever need one..
BTW the new firing pin was stainless, were the original was carbon Steel, I also note that the new pin had a small amount of rust on it, I cleaned it off with a small stainless brush..
Installation was straight forward dropped in the FP & spring then sat the old bushing in place, I used the old bushing because the new one was .003" shorter than the original, So I had to align the roll pin slot ot the top perfectly, Just thumb pressed it in place, See pic..
Then I installed the handy dandy bushing press fixture I made with it's brass base & hammered it in to place watching the side hole for aligment, when it bottomed out it was lined up perfect, I then pressed the New Pin into place padding the revolver with leather scraps & used a Brass punch/drift, when centered it was done.
I still need to measure the Firing pin protrution & give it a range test, I need to aquire some plated case 9mms just in case this 940 has sticky extraction trouble like some I've read about..
Range Report Due!!
Closeup Bushing Side
Bushing Press
Closeup Bushing Installed
940 Done
940 Ready For The range

May 28, 2008, 07:39 AM

Jim Keenan

I am syamsunder a junior member.
Here is your previous text

One reason for the confusion here is that S&W has changed the design of that frame mounted firing pin. In the new design, there is no firing pin bushing. The firing pin comes out to the rear and is held by a slip fit pin that is just pulled out when the side plate is removed. A lot simpler and less costly to make.

Does it mean that in new design a bore is made in to breech plate of diameter to suit F.P base and spring' with concentric small diameter hole ( i think between 1.8 to 2 mm dia ) for F.P small diameter part

Then support given on back by slip fit pin ?

In the photo of F.P of s& w there is a slot visible on base part ( large diameter part ) .is it new design or old design ?

what is the utility of that slot ? Any pin is introduced in to it from side direction from frame that provide sliding as well as retainer function ?
Please draw a hand diagram of the system using windows paint and post.

can you mesure dia (outer )of bushing and let me know ?

thanking you

James K
May 28, 2008, 06:48 PM
I made an error in what I said. I meant to say there is no firing pin bushing pin. There is a firing pin bushing, but it does not need to be removed to remove the firing pin and spring, like it did on the old K-22.

A stepped diameter hole is drilled in from the front; the front part is about .29" and holds the bushing. Rear part is about .157". The bushing is put into the front in the normal manner, then appears to be swaged in to retain it. The firing pin is like the one shown, with a half-moon cut for the cross pin that retains it. The cross pin is a slip fit in the frame and is not visible until the sideplate is removed. Then the cross pin can be removed by simply grasping it with small pliers, and pulling it straight out, at which point the firing pin and spring can come out.

It is a pretty simple setup, and does away with the hammer nose and its retainer pin, eliminating a tricky assembly step (and the associated cost), plus some internal frame machining to direct the hammer nose.. There have been some problems with breaking firing pins (the subject of this thread), but I have no doubt that will be resolved.


May 29, 2008, 05:03 AM

Thank you sir for your kind reply

please see this line diagram and coment if i understood your reply properly or not.

one image is worth thousend words

previously i thought that a through and through hole is made in to breech plate of diameter of bushing.

with the steeped hole there will be support to back of bushing ; from that coller formed.
Am i correct ?

here is another simple idea -threded houseing
please coment

May 29, 2008, 05:41 AM
here is another simple idea -threded houseing

here there is a coller to threaded bushing through which a 3 mm cross pin is passed to give similar function to firing pin
The tip of M-3 bolt can be smoothened to 2 mm ofcourse.
I have added a 8 mm coller to firing pin itself ( there is no insertion problem being an open configaration) this increase area of contact so F.P can face battering from hammer better.
M-6 or m-7 threading can be laid from back side in to breech plate by a tap with extralength of stem attached.
M-7 *1.0 is also an avilable tapset sige.
you have mentioned dia of bushing as 0.29 inch =7.36 mm
This model however occupy 6.5 mm height.

May 31, 2008, 05:25 AM
http://i285.photobucket.com/albums/ll47/syamsunder/ScreenHunter_03May310300.gifThe S&w with lot of establishment & expertise can go for c.n.c product.
I do accept the elegent design of it with Bushing mounted from barrel side which doesent need removel.
Now i have a little doubt. when it is functionally fixed entity it is functioning as stopper to spring & firing pin nose .Only force that pushes it outwards is spring tension probably counteracted by close grinding of its outer dia to match the 1st step in bore of frame ;;; much similar to bearing fitting of general enge works.
The same front stoper function can be achived by making concentric two stepped hole from behind also ; insted of from barrel side; here the frame metal itself make said stoper function.
there should be some practical need to adopt this round about route.
The bushing can be hardended to a higher degree to tolerate hitting from recoil of catridge & primer cup.

Am i correct ? any other reason ?
i also doubt it may be practically difficult make very small dia drill ( 1.8 to 2 mm dia ) at lot of depth on to breech plate to suite dia of firing pin directly.
same can be done easily on to a separate Bushing . Is it the reason ?

Here is the diagram of my proposed Firing pin Houseing with in a threded insert.
Here Firing pin is similarly haveing a step in its base to receive the tip of M-3 bolt which is passed from coller of that threded houseing.
That coller can be provided with a parting slot on its face for tightneing purposes.
This firing pin shape is very similar to S&w without any coller ; not as in my previous diagram posted.
This arrangement takes 5 mm height from breech plate 3 mm for m-3 bolt 1 mm on either side as metal margin.
Did any body in past prepared such arrangement ?

James K
May 31, 2008, 04:42 PM
It might be possible to drill out the firing pin hole from the rear on the hammer guns, but exactly how would one do that on the concealed hammer guns? Drilling from the front also keeps the bushing and firing pin hole concentric with the barrel and is just plain easier.

Threaded bushings are common on break-open shotguns, but require a special tool for removal. Plus there would be additional machine operations to thread the bushing, thread the hole, and drill the disassembly holes, with a fairly large increase in costs and with no discernable advantage. IMHO, the new S&W system is much better.

Remember, it is easy to put stuff on paper or in a CAD program, but a factory engineer has to make something that can actually be produced at a reasonable cost and can be serviced.


June 1, 2008, 07:14 AM
what are the factors that affect nose shape of hammer.
These are the following nose shapes for frame mounted firing pin

1* Flat face
2* flat face with a beck ( a step in vertical direction )

3 Flat face with a verical slot of width a little more than firing pin diameter.

which of them is best ?

Regarding hammer mounted firing pin --- is the diameter of firing pin is same as that of frame mounted firing pin.

June 1, 2008, 08:49 AM
i perfectly agree with you . what all possible on paper is not possible practically.

But what is not possible on paper / thought can nerver be possible practically leaving alone singularities of nature like in certain situations of quantum physics. ( like possible simultanious double existance and parrelel world theories )

Always i see a anology / patteren in predicting gap between thought and practice is like sequencial logical filters.

in dreems we can simply fly defying gravity. but in reality we can't. The gap between thought and external reality is because there is no absolute inner limitation ; but as we start simulating more and more external natures rules in our inner wold ;;more and more closer our imagination to external reality.

But at each stage of adding one more rule the picture changes.

like example here there is natures rules like a thin metal section behaves differently to heat treatment .That fact may not come to mind in initial design.
sir ; when C.N.C machine is at your hand then one process may be easier/ economical.
But when when you are with simple old day machines / lathes tapsets/ files ect with lot of manpower and no problem with time some other process may be cheeper.
so what i am here asking you is ( leave alone cost considerations ) if threaded houseing is having any other FUNCTIONAL PROBLEMS comapared to more advaced model of S&w ?

James K
June 1, 2008, 01:38 PM
Please do not take this wrong, but I have to say that you sound like a college sophomore. (How would I know? Been there. I sounded, I'm sure, just like you.)

FWIW, man's inability to fly like a bird is not related to any lack of imagination, but to purely physical factors, like bone mass and muscle strength.

No, there is no reason not to use a threaded bushing any of your designs would work; as I said, it is common on double shotguns. The bushing is made with two little side holes so it can be removed with a special tool. Inserting the bushing from the rear, though presents other problems, like how do you drill and tap the frame on a concealed hammer gun?

I wonder how much experience you have with CNC machines. They are not magic; any machine operation requires money spent on the machines, the tools, the power and the operator, plus the time and cost of the operation itself. Then the assembler has to screw in the bushing, another time consuming operation. All of that is a lot more costly in time and labor than simply pressing in a bushing and using a swage, all in one pass. In your second design, you introduce another production problem, with another threaded hole and screw to hold in the firing pin. More machine operations, more time, more cost, more difficulty for the gunsmith who has to replace something.

Your design thinking is OK in countries where labor and tools are cheap, and the 10 or 15 seconds to screw in a bushing won't mean much. But designers today, in a competitive environment, don't have the luxury of "cost is no object" that prevailed in older times. A designer or a production engineer of a consumer product who can save ten cents in costs or two minutes of production time is a hero.

There is absolutely nothing wrong with your design, but it is costly and has no advantage. You are falling into a common design trap - starting out to simplify something, and ending up with an even more complex system.

As to the hammer shape, the cutaway hammer face itself has no advantage; it is done for another reason, usually to allow use of a transfer bar system, which S&W does not use.


June 3, 2008, 09:22 AM
Thak you sir for elaborate reply.
i agree the beauty /elegance of s&w design. It is also true that the design i made is much more complex .may be with out much benefit.

I also heard a saying KISS concept ( keep it simple stupid ) where a astronaught tried to make highly complex barometric based pen for space applications ; in ink pen days. ( in space ink pen wont work )Then one of his friends suggested that using pencil is a good alternative. This is an example of KISS concept.


I am left with one doubt.
the recoil force on cartridge and primer is going to push back the firing pin is well known fact.
The area of cross section is small to resist this force by a small pin against a mini step may be 1.5 to 2 mm deep inside base of firing pin ( firing pin base dia = 4 mm nearly )
The cross pin itself is nearly 2.26 mm dia it seems to me when i have taken a tracing on over the photos you have provided.
i wonder how such small stopping surface is working.
I do not deny it is truly working .
(The older frame mounted f.p designs are with a separate recoil plate.
there the f.pin has a collar of about 7 mm dia in front of 4 mm dia zone .)

James K
June 4, 2008, 10:14 AM
The primer does indeed push back on the firing pin, but the firing pin is backed up by the hammer, which in turn is backed up by the mainspring. So the firing pin never actually moves backward in firing and the situation you envision does not occur.

Even in guns with inertia firing pins, like the M1911 pistol, the momentum of the firing pin is sufficient to prevent the primer metal from being forced into the firing pin hole (the so called "pierced primer"). Quite a few people, including some who should darn well know better, think a "pierced primer" is due to a sharp firing pin or too hard a FP blow. In fact, it is due to primer metal being forced backward into the firing pin hole, the result of a too soft firing pin strike.


June 5, 2008, 11:32 AM
1**can i understan that strong hammer main spring is better than week one in preventing peirceing of primers ? so that primer cup will not enter the F.Pin hole ?

2** Is the firing pin dia ( at tip ) of hammer mounted firing pin is same / nearly same as that of frame mounted firing pin ?

I know that tip dia of Frame mounted F.Pin diameter = 1.8 mm to 2 mm .

I am not aware of similar figure of hammer mounted Firing pins .

kindly clarify .
If it is also nearly 1.8 to 2 mm then it needs very narow sloat of 2 mm width need to be made in to breech plate for passage of hammer mounter F.Pin .

I am surprised hoe in olden days of hammer mounted firing pins they are able to make such narrow slot in to breech plate.