Cylinder Locking Up - Primer Flow

I have an older Model 19 with a problem. I am getting frequent light primer hits (approximately 1 in 12, sometimes they will fire if shot again, sometimes not) and recently have had the gun lock up twice.

One previous lock up was with a full-power load but it happened again today with a very light load (11 grains 2400, 158 gr cast). Attached is a photo of both cases (the previously heavier load is the R-P case and the light one is the S-W case). It appears that the primer is flowing back against the firing pin and its opening.

The gun appears to lock up properly and is in time. Yoke and ejector rod do not appear to be bent.


Any suggestions and recommendations? Thank you!

Believe it or not I had a model 65-3 do the same thing! I did a lot of work on the revolver checking headspace,end shake etc and it still did it with most .357 loads I tried.I noticed that the hammer nose was in good shape BUT the spring on the hammer nose was missing.I replaced the spring and have had zero problems with the revolver since.

May be a headspace issue? Jerry Kuenhousen's Smith manual describes how to find and fix this issue. He also has an excellent troubleshooting section is it is another issue.

You don't say how "old" the revolver is, or if you are the original owner, how many rounds through the gun, etc.

The light hits could be a number of things. The mainspring could be modified, the mainspring strain screw could be backed out, or too short, the gun could be dirty, rounds not seated in the chambers properly, dirty chambers or extractor, excessive end shake.....the list goes on.
If these are handloads, the failure to fire may be caused by the primers not be seated properly.

The flow into the hole in the hammer nose bushing could be caused by excessive powder charges, defective primers, or wear to the bushing or hammer nose....or a combination of things. Not all of the hammer noses are spring loaded, so this may or may not be a contributing factor.


If it has been fired alot, perhaps this would be a good time to have it evaluated by a trusted, trained gunsmith, or experienced S&W revolver armorer.

A nice close up of the firing pin bushing may prove interesting.

A main spring that is too light or strain screw that has backed off will cause what you describe, I had the same thing happen to me with a 19-4. I tightened up the strain screw and the problem was solved.

Thanks for the suggestions. Below are the bushing area and the firing pin. The firing pin is not spring loaded. The gun is a 19-3.

Bushing looks fine. and check the mainspring and strain screw for those light hits.

What primers are you using. I'd try small rifle primers.

Forgot to respond on that. The strain screw is all the way in, and doesn't seem to have been filed or anything. I have another mainspring, used, out of a newer gun. I'll try that.

The primers for the first hangup were CCI 550. For the second hangup, Remington. I may try the small rifle. Thanks for the suggestion.

First Question. How "heavy" is the Double Action trigger pull? If you have a trigger gage the weight at break in double action for a 19-3 should be in the 9 to 9 1/2 lbs. range, about 2 lbs. lighter than the current production S&W's. If the DA trigger pull is lighter than this it's quite possible that your Strain Screw has been shortened either by intent or through use.

BTW, the tip of the strain screw can get peened shorter with use and when this happens there will be a sharp burr around the perimeter of the tip of the strain screw. When that burr gets large enough it can interfere with the threads in the frame and make it difficult to remove or potentially damage the threads in the frame. So, anytime you have to remove the strain screw for any reason a good close look with some magnification is an excellent idea. If you find a large burr it can be removed by using a needle file on the tip with it still in the frame using space made available by removing the mainspring.

So, if you have a "short" strain screw the best solution is to purchase a new strain screw from Brownell's or Numrich. A temporary solution is to take a fired primer cup, remove the anvil, and then hammer out the dimple and use that to shim the strain screw to increase the mainspring tension. Just be aware that primer cups are SOFT and will wear fairly quickly, so that is a temporary fix not a permanent solution.

Now, suppose that you don't have a "short" strain screw and you still have misfire problems even with a primer cup added as an additional shim with the DA trigger getting over 12 lbs. First thing to check then is the clearance between the rear of the cyliner and the face of the recoil shield, the "headspace" measurement posted previously. If you have excessive headspace the first thing to check is the End Shake. Because excessive Headspace is almost ALWAYS the result of excessive End Shake. To check End Shake you use valve setting shims to determine the Barrel/Cylinder gap with the cylinder held to the rear and with the cylinder held to the front. The difference between these two measurements is the End Shake and any amount over 0.002 inch should be corrected. BTW, correcting End Shake is something best done by a gunsmith so I won't go into how this is done.

Finally if Headspace checks good and the DA trigger pull is where it should be the only area left to be a likely fault is the Hammer Nose, or as come call it the firing pin. It happens that I recently picked up a 1972 vintage 19-3 that was nearly unfired and it had a "short" hammer nose that was installed at the factory. The solution was a Power Custom Hammer Nose purchased from Brownell's. While it's a spring loaded hammer nose which isn't historically correct for a 19-3 it's an extended length version that can be fitted to a 19-3 and comes with excellent instructions on how to properly fit it to the hammer and frame combination. Note, while not historically correct for the 19-3 the newer spring loaded hammers noses will work perfectly in an older 19-3.

Non-Expert Jimmy:
1. replace mainspring and mainspring tension screw
2. check firing pin and replace if needed
3.clean primer pockets of your cases and INSURE that your primers are FULLY seated.

*** check hammer nose bushing and replace if the opening is not small and round

Thanks for all the suggestions!

I measured the end shake and found what I think was 0.002", so that should be fine. I'll try a new strain screw and go from there.

Is the hammer nose bushing flush with the breech face or has it sunken back into the frame? If you do not have headspace/endshake issues, the primers should not move backwards any appreciable amount unless there is a problem with the hammer nose bushing being pushed back into the frame.

Bruce