What to do now?

[exnodak]

With this post, I am revisiting a problem that I described some time ago. My Model 19-5 snubbie has had fairly frequent misfires with my handloads and CCI primers. They always go bang on the second strike. The primers that do not fire on the first strike always exhibit a noticeably light indentation. I am meticulous about inspecting my loads for proper primer seating, so I don't think that is the problem. I think it is important to note that the same reloads never fail to fire in my other S&W, a 19-3. Also, I use the same primers in two different 9mm semi's, and they always go bang as well. After my previous post, I was advised to check the tightness of the strain screw, and that checked out OK. I don't know what to do with this next. I am no kind of a gunsmith, and am not inclined to tear into this beautiful old revolver. Is this something that S&W would take care of?

[GyMac]

If the primers are properly seated then it may be a light mainspring. You can check this by inserting a spent primer under the strain screw to increase tension on the mainspring. This worked so well for me when I did this to one gun that I have not gotten around to replacing the mainspring.

[big brother]

One more suggestion. Unload the gun and then put it into cocked position with the hammer back as if for single action firing. Now grab the cylinder and try to move it back and forth on the crane. If the cylinder moves enough that you can see it, that is probably where your problem lies. When your hammer falls on the cartridge the whole cylinder is moving foreward. It takes very little play in the fore and aft movement to give you this kind of problem. Time to send it back to S&W if this is the problem.

[chief38]

While the strain screw may be tight, did you check to see if it has been shortened? That would cause the same problem.

If the screw is full length and tightened all the way, try a new main spring. I have had used guns come with bent or modified (Bubba Gun-Smithing) springs that have also caused this problem.

Second to last but not least, and while RARE, check to make sure the grip screw is not pressing against the main spring effectively taking tension off of the spring when the gun is cocked. This did happen to me once and I discovered the grip screw escutcheon had been installed in the grips slightly off. A new set of grips solved the problem.

Have you also checked to see that the hammer is falling freely and not scraping against the inside of the frame? Look for marks on the side of the hammer. If the hammer is not hitting with full force, that could also be causing the problem.

Chief38

[scooter123]

Big Brother is describing End Shake and he is correct in that it can cause misfires. Typically End Shake of 0.002 inch or more should be corrected. The method for doing this historically was by peening the yoke tube to "stretch" it and then re-cutting the end to fit. More recently End Shake shims made from hardened steel have come on the market in 0.002 inch increments making correcting End Shake a matter of removing the Ejector Rod and dropping in a shim in the bore for the enjector rod in the cylinder. These shims can make for a quick and cheap solution so it's a viable option if you are "handy".

Second potential cause is another cheap solution. Strain screws can have the tip peen with use. This has the effect of shortening the strain screw and the fix is to replace the strain screw with a brand new strain screw. BTW, on used revolvers with misfire issues it's pretty safe to assume that the strain screw has been filed at some point, so replacing that screw is the first step for curing a misfire problem. If your model 19 has a strain screw that has peened over or been filed you'll notice the effect very quickly the first time you pull the trigger with a new strain screw in place, because it will get noticeably heavier. For a 19-3 you can safely file that strain screw to produce a DA trigger pull in the 9-9.5 lbs. range and get reliable ignition, so if you find that trigger a bit too heavy you can tune it lighter. However, don't try going too far and an accurate method for measuring trigger pull is something I feel is near critical for tuning triggers. BTW, I use a Lyman Digital, it's easy to use and accurate for triggers of 12 lbs. or less. I'll also note that due to shipping charges I tend to order multiples of critical parts and stash them, last time I ordered strain screws I bought 6 of them.

Next down the list is a mainspring issue. IIRC the factory mainspring is only about 7 or 8 dollars, so they aren't very costly. If you are going to order new strain screws you might as well order a new mainspring at the same time. However, IMO it's actually pretty rare for a FACTORY mainspring to need replacement, by design they are not flexed enough to wear out very quickly. However, aftermarket mainprings at a lighter weight are common so it's not a bad idea to change out the mainspring at the same time you replace the stain screw, especially if you purchased the gun used. BTW, replacing the mainspring can be done without removing the sideplate but you have to fish it in blind. I remove the sideplate to make it easy and if you haven't ever removed a sideplate be sure to ask because there is a trick to doing it correctly. BTW, you tap them free, you do NOT pry them off.

Final area to investigate is the hammer Pivot Pin. Specifically you need to remove the hammer and examine the hammer, frame recess, and sideplate for a heavy rub. If you find a heavy rub look closely at the hole in the sideplate for the hammer pivot pin to see if it's egg shaped. In this event the news isn't good. It indicates that the hammer pivot pin is bent and the hole in the sideplate has "worn in" to this condition. The fix will require installing a hardened bushing in the sideplate and installation of a new hammer pivot pin in the frame. On the plus side this is a VERY rare condition for a revolver that wasn't dropped, so it's unlikely you'll have this problem. However, some level of hammer rub is fairly normal and a light rub can be fixed with the addition of a very thin shim in the correct position. It's unlikely a light rub will cause misfires but it can be unsightly so no harm in adding 0.002 inch of shim if that rub bothers you.

[exnodak]

My thanks to all for all of the great information and suggestions. They give me lots to check out. My one unanswered question , though, is - would S&W analyze and fix this problem on an old out of production gun such as this?

[Dashriprock]

S&W offers a lifetime service policy, so yes -- they would.

But all the above-described fixes are simple and inexpensive and you won't have to ship your revolver at all.

[dfariswheel]

One more, often overlooked issue is a firing pin that's too short.
Sometimes a pin has been replaced with a worn or incorrect pin, or Billy Bob noticed a dented or deformed tip and stoned it to clean it up. In doing so, the pin can get shortened.

Firing pin protrusion can be checked, but it's most easily done with a special firing pin protrusion gauge and a micrometer.

In any case, S&W will repair the gun and give it a complete check up and cleaning while they have it.

[exnodak]

I checked the end shake per suggestions here, and there is no discernible play. I removed the Hogue grips, and inspected the strain screw which appears to be tight and unaltered. Also looked at some Youtube videos on replacing the mainspring.
I bought the gun used, but it appeared to be practically unfired. I really would rather not work on it unless I can positively identify the problem. Maybe sending it to S&W is the best approach?

[m1gunner]

Originally Posted by exnodak

I checked the end shake per suggestions here, and there is no discernible play. I removed the Hogue grips, and inspected the strain screw which appears to be tight and unaltered. Also looked at some Youtube videos on replacing the mainspring.
I bought the gun used, but it appeared to be practically unfired. I really would rather not work on it unless I can positively identify the problem. Maybe sending it to S&W is the best approach?

The work is not difficult, and the only special tools you need fir the main spring/strain screw work are properly fitting screwdrivers.

But, if you aren't comfortable taking the gun apart and down to the individual parts, by all means, send it to S&W.

They have the parts, ALL the tools, and the skilled hands to bring your revolver up to like new condition.