Is the hammer strike lighter in rapid double action?

[lefty_jake]

A number of years ago I experienced a Smith & Wesson revolver that had occasional misfires when I shot it double action, but it worked fine for other shooters. The other shooters were shooting double action, but they were shooting quite slowly and staging the trigger. When I shoot double action, I pull the trigger briskly straight through.

My suspicion is that if the trigger is pulled quickly that it can slip out from under the hammer just a little more easily. And if the double action trigger is staged slowly, then the hammer may be cammed back just a few thousandths farther than if the trigger is pulled quickly. If the mainspring weight is marginal, then moving the hammer back a very small extra distance could matter.

More recently, I have had another similar experience. A friend of mine got two misfires in 100 rounds of double action shooting. He pulls the double action trigger slowly. I thought his mainspring felt a little light, and I asked if I could shoot the gun. I got three misfires in 40 rounds of rapid double action. He replaced the mainspring and there have been no misfires since.

Of course with the small number of misfires involved, the observed results could just be coincidence. So the question is, has anyone else experienced something like this? Is the hammer strike a tiny bit lighter during very rapid double action than during slow double action? If so, do you have thoughts on why?

 

[reddog81]

I'd verify the misfires aren't due to off center primer hits. It might be possible the rapid fire double action could be causing the gun to not lock up correctly and you're not hitting the primer squarely in the center. I have no experience with this but it's the first thing that popped into my head.

Pulling the trigger slowly could result in a failure to lock up and pulling to fast might cause the cylinder to over rotate.

 

[mxbob]

I recently had a similar expierence with a new to me N frame. All I had to do was tighten the strain screw
Bob Ray 1815

 

[pittpa]

FWIW my Python was more likely to light strike on staged double action. Have not experienced it on a SW revolver.


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[italiansport]

I had this problem(misfires in DA) with a Model 28 at one time. I replaced the mainspring and the problem went away.
Jim

 

[shawn mccarver]

By definition, the hammer does not go back as far in DA as it does when cocked in SA mode. That said, if you are having light strikes in DA, then return to factory return spring, mainspring, and strain screw, and see if the problem goes away. These things seem to happen only after attempting to lighten the trigger pull. Putting the revolver on the edge of unreliability is ok for a match or range gun, I suppose, but not for a defense gun. In actuality, it is not even ok on a match or range gun as far as I am concerned. But, there are plenty of people out there who seem not to care about reliability.

 

[tomcatt51]

In actuality, it is not even ok on a match or range gun as far as I am concerned. But, there are plenty of people out there who seem not to care about reliability.

Really? Do you compete or shoot matches or are you just bashing those who set up guns for competition because we violate your sense of what's "right"? Reliability is a MAJOR issue when setting up a gun for USPSA, Steel Challenge, ICORE, PPC etc. Building reliable guns for competition that go thru much more ammo than most folks guns ever do gives us a very good knowledge base for reliable carry guns too. The only competition I can think of where you get a "do over" if you have a mis-fire is bullseye.

 

[Protocall_Design]

The hammer moves the same distance to the rear on DA whether pulled slowly or quickly. Mechanically it cannot be otherwise.

There can be other issues that cause misfires such as timing, lockup, endshake, headspace, seating of primers (either too deep or not deep enough), spring tension, hammer weight, trigger stop, firing pin, etc.

 

[chief38]

A Revolver's hammer moves more toward the rear when cocked in the SA mode. When in the DA mode it falls earlier than when it does in the SA mode causing less travel and a less strike force. I'd think that your Revolver has been worked on and is just light enough to work when shot in the SA mode. Who ever shortened the Strain Screw or lightened the Main Spring went a bit too far. An easy fix as soon as you determine the exact problem IF due to what I just mentioned.

 

[k22fan]

Comparison of DA to SA hammer fall distance is not the issue here.

Normal wear eventually caused the old V mainspring Colt double actions to go out of time. After going out of time the cylinder would still be rotating when the firing pin hit giving the firing pin indentation a curved tail. That resulted in more missfires. Many S&Ws depend on cylinder momentum to spin the cylinder the last few degrees into lock up. I do not see how pulling the trigger faster could change hammer fall but it should give the cylinder more momentum and spin it into lock up sooner. Reflecting on my experiences with out of time Colts I would have guessed that pulling the trigger faster would result in less missfires, the opposite of what the original poster observed.

What do I know? One way or the other the solution is usually a heavier mainspring, turning the strain screw in or replacing a shortened strain screw.

 

[jaymoore]

Definitely too marginal mainspring tension regardless, but if you are looking for causes, there's several good leads above, plus watch for signs of hammer rub against the frame. May be caused by something so simple as cycling the revolver with the sideplatr off but with full spring tension.

Also, whether you exert direct rearward pressure on the trigger or have some side bias can change geometry a bit.

Very fringe stuff. As noted above, if there's nothing grossly wrong just up the mainspring tension. It won't change trigger pull weight near as much as the trigger return spring. It may even reduce trigger stacking, if the tension screw is really backed off or short. Older S&Ws have been noted with quite a variety of tension screw lengths, so beware swapping them willy-nilly.

 

[scooter123]

These things seem to happen only after attempting to lighten the trigger pull.

Not true, there are other potential causes for "light strikes" than a lightened mainspring. One example is my 19-3, which was nearly unfired when I purchased it a while back. Turned out that the reason it was nearly unfired was because the factory installed Hammer Nose was short. So short it wouldn't light off a 357 Magnum in double action and had a 60% failure rate with 38 special ammunition.

Yeah, S&W made mistakes back in the Bangor Punta era, lot's and lot's of mistakes according to some shops I used to visit back in the 70's. At the time I thought they were just pushing Colt revolvers but this 19-3 gives evidence they may have had good reason for complaining about S&W's quality.

The solution was to install a Power Custom Hammer nose and my 19-3 has become my current favorite revolver to shoot.

As for the question about staging the trigger improving reliability, that is something that would be contrary to Classic Physics. In theory if you were to pull the trigger quickly enough you would be able to impart enough Inertia to the hammer to have it actually "carry past" the release point for the DA sear and thus create MORE tension in the mainspring than when staging the trigger slowly. OF course unless you are Jerry Miculek it's probably unlikely you could pull a trigger that quickly but in theory a faster trigger stroke does have the potential to improve reliability.

 

[Protocall_Design]

Lear Seigler and Bangor Punta both created an era of poor quality S&W revolvers. I have seen everything from good to horrible and every variation in between. On some of those you have to almost rebuild the gun before doing an action job.

 

[mike campbell]

As noted above, if there's nothing grossly wrong just up the mainspring tension. It won't change trigger pull weight near as much as the trigger return spring.

Say what?

Changing a trigger return spring will alter SA pull by 1-2 lbs (up to 50%) and have negligible effect on DA pull.

Altering mainspring tension can have negligible effect on SA pull but can change the DA pull by 6 lbs....also 50%.

 

[lefty_jake]

I want to thank everyone who contributed to this thread. The responses have made it clear that the hammer strike is the same regardless of the speed of the trigger pull. The cases I observed which seemed to have more misfires with a faster trigger pull were most likely caused by coincidence or by other aspects of the guns being out of spec.

For those who commented about increasing the mainspring tension, that was indeed the solution, but I still wanted to have a better understanding of the underlying problem.

Thank you all for your help.