What might cause a light strike?

COASTER · June 4, 2014, 10:56 PM

Hi folks,

Last time I was at the range, I was shooting Federal 158 gr JSP 357 mag ammo in my SW 686 and experienced three light strikes( I hope that is the right word for it) i.e. On pulling the trigger, the gun went "click" but when I pulled the trigger again it shot fine.

This happened over 100 rounds. I have never had this happen with my 686.
Any opinions on what might have caused it?

My revolver was clean and lubricated, factory ammo and no other issues or symptoms before I had this experience at the range.

I appreciate any information

gyvel · June 4, 2014, 11:07 PM

Dirt or fouling in the firing pin hole in the recoil plate; Dirt or fouling inside the hammer where the firing pin swivels; hard primers; a small burr causing the hammerfall to be cut short by 1 or 2 thousandths as well as slightly cushioning the blow; slightly loose sideplate; to name a few.

Webleymkv · June 5, 2014, 12:08 AM

The first thing I check when a S&W has light primer strikes is the strain screw (located on the bottom front of the grip frame). Many people erroneously think this is a trigger pull adjustment and back it out to lighten the pull, but doing so often causes light strikes. The strain screw should be tightened down as far as it will go.

gyvel · June 5, 2014, 06:44 PM

Yes^^^^^^^^^^^^^. I forgot the most basic, obvious thing: The strain screw. I always assume that people have not messed with it.

COASTER · June 5, 2014, 09:31 PM

Thank you gyvel and Webleymkv for your insight--
I have not touched the strain screw but will check its tightness now that I learned something. I will also check out the other things you mentioned. I know for sure that I clean all of the visibly dirty places but I will be sure to check out the things you both mention.

Webleymkv · June 5, 2014, 10:29 PM

You didn't mention whether the gun was bought new or used. If it's used, it is possible that the previous owner fiddled with the strain screw. I've seen S&W's before that developed light strike issues some time after the strain screw was backed out. This is because while even backed out slightly it still puts enough tension on the mainspring to pop primers, but because there is no torque on the screw it continues to back out under recoil.

If one is going to reduce tension on the mainspring via the strain screw, the proper way to do so is by removing a small bit of metal from the end of the screw and then tightening it down all the way. I do not, however, recommend this as it is too easy to take too much metal off the screw. If one really wants to lighten the trigger on a S&W revolver, it's better, IMHO, to simply install a reduced power mainspring and/or rebound slide spring as those modifications are easily reversed if they cause functioning issues.

COASTER · June 5, 2014, 11:09 PM

Webleymkv-
My 686 magnum is used which I bought from a local shop - it was an LEO gun. I hear what you are saying and will take a close look this wknd and check in on what I find.
Thanks for the valuable info.

Japle · June 6, 2014, 10:17 AM

All my S&W revolvers have one of these installed:

http://www.midwayusa.com/product/926...rame-revolvers

It's cheap and easy and excellent insurance against "light strikes".

James K · June 6, 2014, 11:04 AM

Have you fired ammo from that lot before with no problems? What do the primers of the misfires look like (or did you retry all of them)?

The problem with light strikes is that a misfire due to a bad/dead primer may look like a light strike because the primer does not have the flowback around the firing pin mark that we associate with a primer that fired normally. That makes a primer that didn't fire look a lot like a light strike.

Jim

COASTER · June 7, 2014, 12:11 AM

Japle- intriguing - I will look into this, thank you for the link and information.

James K - unfortunately, I refired ( in same session) all of the ones that I thought were subject to - light strikes, so those are gone.
As far as having used the same stock Ammo before- yes, I have used this type of ammo before with no issues.
I thank you for showing me another avenue to investigate-

So, looks like I am back to the drawing board- I am thinking to get another batch of Federal ammo similar to the ones I just fired and if I run into similar issues, I will unload the individual round / s and check in with pictures and post them.

Intrigued

Webleymkv · June 7, 2014, 02:34 AM

Depending on the vintage of your revolver, the firing pin in Japle's link may or may not work. The firing pin in that link is for S&W revolvers with frame-mounted firing pins (a feature that was introduced on the 686-5 in 1997). An older specimen (686 no-dash through 686-4) will have the firing pin (or hammer nose in S&W lingo) mounted on the hammer itself.

It's mildly unusual that you would have issues with Federal ammunition because Federal is generally thought to have the "softest" primers. If you don't have any more issues with another box of Federal ammo and still want to be sure that it was the ammo and not the gun causing the issues, try a box of Sellier & Bellot or CCI/Speer ammo as those brands are often regarded as having "hard" primers.

James K · June 7, 2014, 12:00 PM

FWIW, maybe my comment about primers deserves a bit more explanation. Priming compound is a true high explosive. When a primer fires, high pressure from within the primer itself forces the primer metal back around the firing pin, creating the kind of crater we usually see and think of as "normal".

But if the primer doesn't fire, the firing pin produces only a small "dent", since the firing pin is stopped by the anvil before it will actually make a deep crater in the primer.

Only close examination can show if the latter type of "dent" has resulted from a light firing pin blow or from failure of the primer to fire. However, if misfires occur along with "pierced" primers (hole in primer with a small disc blown out), it is certain that the cause is light primer strikes caused by low mainspring tension or a too-light firing pin. So-called "pierced" primers are the result of the pressure inside the primer overcoming the firing pin inertia and forcing the firing pin back so primer metal is blown into the firing pin hole.

Jim

June 4, 2014, 10:56 PM	#1
COASTER Member Join Date: December 3, 2004 Posts: 81	What might cause a light strike? Hi folks, Last time I was at the range, I was shooting Federal 158 gr JSP 357 mag ammo in my SW 686 and experienced three light strikes( I hope that is the right word for it) i.e. On pulling the trigger, the gun went "click" but when I pulled the trigger again it shot fine. This happened over 100 rounds. I have never had this happen with my 686. Any opinions on what might have caused it? My revolver was clean and lubricated, factory ammo and no other issues or symptoms before I had this experience at the range. I appreciate any information

June 4, 2014, 11:07 PM	#2
gyvel Senior Member Join Date: August 30, 2009 Location: Northern AZ Posts: 7,172	Dirt or fouling in the firing pin hole in the recoil plate; Dirt or fouling inside the hammer where the firing pin swivels; hard primers; a small burr causing the hammerfall to be cut short by 1 or 2 thousandths as well as slightly cushioning the blow; slightly loose sideplate; to name a few.

June 5, 2014, 12:08 AM	#3
Webleymkv Senior Member Join Date: July 20, 2005 Location: Indiana Posts: 10,446	The first thing I check when a S&W has light primer strikes is the strain screw (located on the bottom front of the grip frame). Many people erroneously think this is a trigger pull adjustment and back it out to lighten the pull, but doing so often causes light strikes. The strain screw should be tightened down as far as it will go.

June 5, 2014, 06:44 PM	#4
gyvel Senior Member Join Date: August 30, 2009 Location: Northern AZ Posts: 7,172	Yes^^^^^^^^^^^^^. I forgot the most basic, obvious thing: The strain screw. I always assume that people have not messed with it.

June 5, 2014, 09:31 PM	#5
COASTER Member Join Date: December 3, 2004 Posts: 81	Thank you gyvel and Webleymkv for your insight-- I have not touched the strain screw but will check its tightness now that I learned something. I will also check out the other things you mentioned. I know for sure that I clean all of the visibly dirty places but I will be sure to check out the things you both mention.

June 5, 2014, 10:29 PM	#6
Webleymkv Senior Member Join Date: July 20, 2005 Location: Indiana Posts: 10,446	You didn't mention whether the gun was bought new or used. If it's used, it is possible that the previous owner fiddled with the strain screw. I've seen S&W's before that developed light strike issues some time after the strain screw was backed out. This is because while even backed out slightly it still puts enough tension on the mainspring to pop primers, but because there is no torque on the screw it continues to back out under recoil. If one is going to reduce tension on the mainspring via the strain screw, the proper way to do so is by removing a small bit of metal from the end of the screw and then tightening it down all the way. I do not, however, recommend this as it is too easy to take too much metal off the screw. If one really wants to lighten the trigger on a S&W revolver, it's better, IMHO, to simply install a reduced power mainspring and/or rebound slide spring as those modifications are easily reversed if they cause functioning issues.

June 5, 2014, 11:09 PM	#7
COASTER Member Join Date: December 3, 2004 Posts: 81	Webleymkv- My 686 magnum is used which I bought from a local shop - it was an LEO gun. I hear what you are saying and will take a close look this wknd and check in on what I find. Thanks for the valuable info.

June 6, 2014, 10:17 AM	#8
Japle Senior Member Join Date: October 12, 2004 Location: Viera, Florida Posts: 1,340	All my S&W revolvers have one of these installed: http://www.midwayusa.com/product/926...rame-revolvers It's cheap and easy and excellent insurance against "light strikes".

June 6, 2014, 11:04 AM	#9
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Have you fired ammo from that lot before with no problems? What do the primers of the misfires look like (or did you retry all of them)? The problem with light strikes is that a misfire due to a bad/dead primer may look like a light strike because the primer does not have the flowback around the firing pin mark that we associate with a primer that fired normally. That makes a primer that didn't fire look a lot like a light strike. Jim

June 7, 2014, 12:11 AM	#10
COASTER Member Join Date: December 3, 2004 Posts: 81	Japle- intriguing - I will look into this, thank you for the link and information. James K - unfortunately, I refired ( in same session) all of the ones that I thought were subject to - light strikes, so those are gone. As far as having used the same stock Ammo before- yes, I have used this type of ammo before with no issues. I thank you for showing me another avenue to investigate- So, looks like I am back to the drawing board- I am thinking to get another batch of Federal ammo similar to the ones I just fired and if I run into similar issues, I will unload the individual round / s and check in with pictures and post them. Intrigued

June 7, 2014, 02:34 AM	#11
Webleymkv Senior Member Join Date: July 20, 2005 Location: Indiana Posts: 10,446	Depending on the vintage of your revolver, the firing pin in Japle's link may or may not work. The firing pin in that link is for S&W revolvers with frame-mounted firing pins (a feature that was introduced on the 686-5 in 1997). An older specimen (686 no-dash through 686-4) will have the firing pin (or hammer nose in S&W lingo) mounted on the hammer itself. It's mildly unusual that you would have issues with Federal ammunition because Federal is generally thought to have the "softest" primers. If you don't have any more issues with another box of Federal ammo and still want to be sure that it was the ammo and not the gun causing the issues, try a box of Sellier & Bellot or CCI/Speer ammo as those brands are often regarded as having "hard" primers.

June 7, 2014, 12:00 PM	#12
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	FWIW, maybe my comment about primers deserves a bit more explanation. Priming compound is a true high explosive. When a primer fires, high pressure from within the primer itself forces the primer metal back around the firing pin, creating the kind of crater we usually see and think of as "normal". But if the primer doesn't fire, the firing pin produces only a small "dent", since the firing pin is stopped by the anvil before it will actually make a deep crater in the primer. Only close examination can show if the latter type of "dent" has resulted from a light firing pin blow or from failure of the primer to fire. However, if misfires occur along with "pierced" primers (hole in primer with a small disc blown out), it is certain that the cause is light primer strikes caused by low mainspring tension or a too-light firing pin. So-called "pierced" primers are the result of the pressure inside the primer overcoming the firing pin inertia and forcing the firing pin back so primer metal is blown into the firing pin hole. Jim