Testing firing pin function without live ammo?

[Boulder]

Hi Everyone,

Is there a way to test firing pin function without live ammo? I also don’t have reloading supplies.

For various reasons, it’s difficult for me to get to a range right now to test my 2.5” 686+. But I noticed that the firing pin doesn’t protrude very much when pulling the trigger with the cylinder release pulled back. I don’t have any tools to measure exact length. It definitely protrudes a lot less than my other S&W revolvers. And the tip of the firing pin is “pointier” than most others. With the hammer back, I can manually push the firing pin a little further out. But it’s still not as much as my other revolvers. I’m guessing I need to actually fire the thing to see if the inertia firing pin is capable of reliably igniting primers? I did check after reading other posts, that the strain screw is tight. When I do a pencil test, it only moves about an inch.

Another revolver I have that also doesn’t move the pencil much is a 696-ND. But it has a hammer-mounted pin. Is this something specific to L-frames? All my other Smiths really make the pencil fly out much further - whether old or new production, hammer or frame mounted firing pins.

Idea of things to try? Thanks for any suggestions.

 

[Sevens]

A pencil with a typical pink eraser or a Bic-type ball point pen, cap removed with plastic end cap.

Hold handgun with muzzle directly up, pen or pencil will typically go skyward.

 

[Scharfschuetzer]

I think that an inch is enough.

If you reload, you can also prime some empty cases and then test the revolver. That will confirm it one way or another. You might get some primer back out which might cause friction against the recoil plate. You can stop that by drilling out the flash holes slightly larger.

Speer also markets plastic cases and bullets for primer only practice. Check the web sights for them. Of course primers are about Unobtanium, so you might be back to the pencil thing again.

 

[chief38]

New snap caps can be used as well.

 

[Pef]

I have a couple of Smiths in which the firing pin barely protrudes from the bushing when the hammer is at rest. Yes, it would seem like it's not enough for ignition, but each of those revolvers fire without fail.

The pen trick mentioned above will do, but once you get out to the range, I'm sure you'll be satisfied.

Of course, if you have a vise, you could always pull the bullet, empty the powder and then load and fire! Wear earplugs and point in a safe direction! A primer can host of violent little expolsion.

 

[VictorLouis]

1- I noticed that the firing pin doesn’t protrude very much when pulling the trigger with the cylinder release pulled back.

2 - With the hammer back, I can manually push the firing pin a little further out.

3 - Another revolver I have that also doesn’t move the pencil much is a 696-ND. But it has a hammer-mounted pin.

Is this something specific to L-frames? .

1 - Subjective, but I know what you mean.
2 - The part that counts is THIS. It's spring-loaded on the newest gen revolvers. *** When the hammer smacks it, it WILL extend to its fully-forward range of travel.
3 - Yes, the older pin is obviously fixed-in place, and has but one length of travel. Try the hard-capped end of the typical Bic style pen, as was suggested. You should see a bit more oomph. Remember, that rubber pencil eraser soaks up a lot of that firing-pin impact.

Now, what I've done for years is what you describe in #1. However, I squish the tip of my left index finger against the recoil plate to FEEL the impact of the firing-pin. It shouldn't be painful, per se, but it ought to be such you don't want to repeat it real soon, LOL. Try THAT little exam on both of your L-frames, and I bet you may be hard-pressed to sense the difference. Just give your fingertip time to recover from the first one.

***I tried to open and check a used 442-1 J-frame at a shop once. Cylinder wouldn't open. Naturally, you might think the ejector rod was unscrewed. Turns out, the firing-pin was jammed forward, and somehow cocked over to bear against the lip of the chamber. Spring was obviously mangled. Hmmm......dry-fired much?

 

[lefty_jake]

For revolvers like yours with a FMFP (frame mounted firing pin), I recommend to take the firing pin out and measure it. Over the years, these firing pins have been made with a variety of lengths and tip shapes.

I believe the nominal length for factory firing pins is .495. If it is less than .492, I replace it. Some people replace them if they are under .495.

A few years ago I bought some factory replacement pins, and they are .493 to .495 in length. They work fine. I have not bought any recently, but I would hope that current factory production is also fine. There are also aftermarket options, but I prefer using all factory stock parts when possible.

Note that there are lots of revolvers with shorter firing pins that work just fine. But I believe that is dependent on strong springs, and close tolerances for headspace, end shake, etc. I think a longer stock firing pin gives a little more margin for future wear.

On revolvers with the FMFP, the firing pin is easy to remove and replace. However, you need to have the right screwdrivers, and know how to remove the sideplate. It is easy to damage the screws and the sideplate if you are not careful.

Anyone who is mechanically inclined and has the right tools can do this job, but it is also fine and recommended to seek assistance if you are not familiar with opening up revolvers.

 

[2152hq]

The firing pin rebounds a short distance after being wacked. That rebound is to avoid the pin sticking in a primer and jamming up the action.

A primed case used for testing wether a gun will go bang or not is a very common thing around shops. They can be loud though.
I usually wrap a towel or other cloth around the muzzle (and the bbl gap on a rev) to silence the noise if I don't want to disturb the cats and dogs.
Yes check the cloth afterwards for sparks, ect.
A primed case can have it's primer back out after firing and sometimes make the revolver a little tough to open, so be aware of that. It's not the guns fault.

The launched pencil is pretty good.
But I like to use a plain hardwood dowel with the end filed or ground nice and flat.
Place the dowel down the bore and hold it firmly up against the breech face.
The largest dia dowel that you can fit down the bore makes for the easiest test as it will pretty much center itself against a CF firing pin.
No need for a tight fit dowel,,just a sliding drop in fit.

Hold the dowel firmly against the breechface (remember you have to cock the revolver first before dropping the dowel thru the cylinder!)

Then fire the hammer and let the firing pin indent itself into that end face of the dowel.
Pull the dowel out and examine the imprint.
It will be very close to what a fired primer will look like in depth and dia.

A weak strike or other problem can usually be seen in the imprint.

You can also then use the dowel for the launch test as well. Visual effect is a great thing.

File the end back smooth and use it over again.

 

[s&wchad]

A pencil with a typical pink eraser or a Bic-type ball point pen, cap removed with plastic end cap.

Hold handgun with muzzle directly up, pen or pencil will typically go skyward.

I’ve done that for decades. Sometimes they really take off!

I’ve also got a short piece of 1/2” wooden dowel rod that I use to check shotguns.

 

[vinn]

i have a s&w revolver with a protuing fireing pin. can not close the cylinder when loaded. i think -- the sear is worn down from years for fireing. i will replace the hamer.

 

[nedlate]

I’m guessing I need to actually fire the thing to see if the inertia firing pin is capable of reliably igniting primers?

I think I would do this first before worrying about firing pin protrusion, ect.
You have not fired the gun since purchasing it?
Ed

 

[Hair Trigger]

Slip a piece of business card between the cylinder and recoil shield and fire it double action. The hammer nose should heavily indent the business card, almost to the point of piercing it, demonstrating it travels far enough to do the same to a primer.

 

[stansdds]

The pencil test works well, but I recommend using an un-sharpened pencil... unless you like little holes in your ceiling. I speak from experience.