What might cause this: trigger locks up during dry firing.

Pond, James Pond · July 31, 2015, 10:05 AM

Never had this before.

It's my Astra 680 .38Spl snub. I was doing some rapid dry-firing to just strengthen my trigger finger in DA as well as getting used to the pull and break. I also sometimes pull the trigger through DA to the point of break once the cylinder has locked up.

The gun is loaded up with brass-capped snap-caps to protect the pin. They are quite used, so the strike zone is cratered from pins strikes, but it is still connecting as I can see the rim get shoved forward when the pin hits.

As I was doing this today several times my revolver locked up. From the shooter's perspective the cylinder rotates counter-clockwise and to free up the action I'd have to rotate the cylinder clockwise by a fraction of a degree: barely perceptible. Without doing so the trigger is solid: no movement.

This being my carry gun, it is of course worrying that it might lock up that way when I'm in a tight spot. Murhpy's Law and all that...

Just to give you an idea it locked up after 46 DA shots, then 29, then 77 shots, so it is not that predictable but is certainly to frequent for comfort.

On the other hand it has never happened before.

Could it be the snap-caps?
What might make the cylinder "over-rotate"?

Thoughts?

gyvel · July 31, 2015, 10:21 AM

I thought only the Ruger SP 101 had that problem.

Pond, James Pond · July 31, 2015, 10:33 AM

Clearly not. But what causes it?

I'm going to try cleaning up the edges of my snap-caps to stop any drag on the back-plate of the frame

Doyle · July 31, 2015, 10:38 AM

The hand is slightly "over rotating" the cylinder. Ordinarily, the cylinder stop (little bulge on the bottom of the frame that springs up to engage the cylinder) would pop up into the cylinder stop groove and stop the rotation. I suspect that the cylinder stop either isn't moving freely (gummed up) or isn't moving up with enough force (weak cylinder stop spring).

James K · July 31, 2015, 10:39 AM

The usual reasons for the cylinder over-rotating is either that the cylinder stop does not rise in time to engage the stop notch or the stop or notch is worn and the engagement is insufficient.

It is usually possible to see the latter just by looking at the cylinder notches and the cylinder stop. A slow cylinder stop can be caused by a weak spring or by some interference, like dirt.

Jim

Pond, James Pond · July 31, 2015, 10:46 AM

I recently stripped and cleaned the lot and the stop seemed fine and the spring clearly worked as it made a bid for freedom at the far end of the room. Took me 15 min to find it!! The stop's edges are sharp and the stop grooves are clean.

Anyway, by no means conclusive, but having filed the brass peen from around the pin crater on the caps and I snapped until my forearm cramped and it didn't happen.

Coincidence? Could drag from the caps cause the problem?

Doyle · July 31, 2015, 11:05 AM

Drag would cause under rotation, not over rotation. I'm still thinking the stops aren't doing their job.

One thing you need to do - mark your cylinders with a grease pencil and see if it does it randomly or if it is always the same cylinder.

Snyper · August 6, 2015, 09:57 PM

Quote:

I recently stripped and cleaned the lot

That's one of the most common causes of firearm malfunctions

MrBorland · August 7, 2015, 07:11 AM

Your Astra has a free floating frame-mounted firing pin, no? If so, a broken FP spring (or pin itself) can cause the troubles you describe.

With no cases in the cylinder, dry fire once, then look into the little space in front of the FP bushing. Or simply hold the gun muzzle-down. You shouldn't see the tip of the FP protruding. If the FP is protruding, the tip of the FP is binding the cases when you're dry firing.

If so, and you're able to easily push it back with your finger, the spring's likely kaput (or the pin itself broke). If it's protruding, and it takes quite a bit of effort to push the pin back in, the FP's binding, and may take a little strategic stoning to relieve some extra metal.

Chuck Dye · August 7, 2015, 11:35 AM

I cannot contribute on the mechanical problem but can recommend getting a Gripmaster for the trigger finger exercise. I found the black, heavy, model too much and suggest getting a lighter model, perhaps approximating the double action pull weight of your revolver.

I have seen Gripmasters with crude plastic gun sights attached that might make for more effective practice in addition to the strength building but none of the owners could cite a source and my casual search failed to locate a vendor. YMMV

Pond, James Pond · August 7, 2015, 12:35 PM

Quote:

Your Astra has a free floating frame-mounted firing pin, no? If so, a broken FP spring (or pin itself) can cause the troubles you describe.

With no cases in the cylinder, dry fire once, then look into the little space in front of the FP bushing. Or simply hold the gun muzzle-down. You shouldn't see the tip of the FP protruding. If the FP is protruding, the tip of the FP is binding the cases when you're dry firing.

Interesting.

Although it has not given me trouble since filing down the pin-strike peen on the snap-caps, I will definitely have a look at it once home. (weekend away, from today!

)

Skeets · August 14, 2015, 10:52 PM

An S&W armorer told me I was"outrunning"my M34 trigger design.Slowed downed,never happened again.Just a thought...

Pond, James Pond · August 15, 2015, 01:48 AM

Since tidying up the snap-caps it hasn't happened again but I certainly would not want a trigger design in a carry gun that requires me to slow down!! That gun should be working at my speed, not vice versa!!

Skeets · August 15, 2015, 04:13 AM

Glad your up and running James,Good Shooting!

Pond, James Pond · August 15, 2015, 04:31 AM

Don't know about good shooting, but certainly fun!!

July 31, 2015, 10:05 AM	#1
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	What might cause this: trigger locks up during dry firing. Never had this before. It's my Astra 680 .38Spl snub. I was doing some rapid dry-firing to just strengthen my trigger finger in DA as well as getting used to the pull and break. I also sometimes pull the trigger through DA to the point of break once the cylinder has locked up. The gun is loaded up with brass-capped snap-caps to protect the pin. They are quite used, so the strike zone is cratered from pins strikes, but it is still connecting as I can see the rim get shoved forward when the pin hits. As I was doing this today several times my revolver locked up. From the shooter's perspective the cylinder rotates counter-clockwise and to free up the action I'd have to rotate the cylinder clockwise by a fraction of a degree: barely perceptible. Without doing so the trigger is solid: no movement. This being my carry gun, it is of course worrying that it might lock up that way when I'm in a tight spot. Murhpy's Law and all that... Just to give you an idea it locked up after 46 DA shots, then 29, then 77 shots, so it is not that predictable but is certainly to frequent for comfort. On the other hand it has never happened before. Could it be the snap-caps? What might make the cylinder "over-rotate"? Thoughts? __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly. Last edited by Pond, James Pond; July 31, 2015 at 10:12 AM.

July 31, 2015, 10:21 AM	#2
gyvel Senior Member Join Date: August 30, 2009 Location: Northern AZ Posts: 7,172	I thought only the Ruger SP 101 had that problem. __________________ As always, YMMV. __________________________________________ MIIAA SIFE

July 31, 2015, 10:33 AM	#3
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	Clearly not. But what causes it? I'm going to try cleaning up the edges of my snap-caps to stop any drag on the back-plate of the frame __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly. Last edited by Pond, James Pond; July 31, 2015 at 10:40 AM.

July 31, 2015, 10:46 AM	#6
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	I recently stripped and cleaned the lot and the stop seemed fine and the spring clearly worked as it made a bid for freedom at the far end of the room. Took me 15 min to find it!! The stop's edges are sharp and the stop grooves are clean. Anyway, by no means conclusive, but having filed the brass peen from around the pin crater on the caps and I snapped until my forearm cramped and it didn't happen. Coincidence? Could drag from the caps cause the problem? __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

August 7, 2015, 07:11 AM	#9
MrBorland Senior Member Join Date: May 31, 2007 Location: NC Posts: 2,614	Your Astra has a free floating frame-mounted firing pin, no? If so, a broken FP spring (or pin itself) can cause the troubles you describe. With no cases in the cylinder, dry fire once, then look into the little space in front of the FP bushing. Or simply hold the gun muzzle-down. You shouldn't see the tip of the FP protruding. If the FP is protruding, the tip of the FP is binding the cases when you're dry firing. If so, and you're able to easily push it back with your finger, the spring's likely kaput (or the pin itself broke). If it's protruding, and it takes quite a bit of effort to push the pin back in, the FP's binding, and may take a little strategic stoning to relieve some extra metal. Last edited by MrBorland; August 7, 2015 at 07:18 AM.

July 31, 2015, 10:38 AM	#4
Doyle Senior Member Join Date: June 20, 2007 Location: Rainbow City, Alabama Posts: 7,167	The hand is slightly "over rotating" the cylinder. Ordinarily, the cylinder stop (little bulge on the bottom of the frame that springs up to engage the cylinder) would pop up into the cylinder stop groove and stop the rotation. I suspect that the cylinder stop either isn't moving freely (gummed up) or isn't moving up with enough force (weak cylinder stop spring).

July 31, 2015, 10:39 AM	#5
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	The usual reasons for the cylinder over-rotating is either that the cylinder stop does not rise in time to engage the stop notch or the stop or notch is worn and the engagement is insufficient. It is usually possible to see the latter just by looking at the cylinder notches and the cylinder stop. A slow cylinder stop can be caused by a weak spring or by some interference, like dirt. Jim

July 31, 2015, 11:05 AM	#7
Doyle Senior Member Join Date: June 20, 2007 Location: Rainbow City, Alabama Posts: 7,167	Drag would cause under rotation, not over rotation. I'm still thinking the stops aren't doing their job. One thing you need to do - mark your cylinders with a grease pencil and see if it does it randomly or if it is always the same cylinder.

August 7, 2015, 11:35 AM	#10
Chuck Dye Senior Member Join Date: June 28, 2002 Location: Oregon-The wet side. Posts: 949	I cannot contribute on the mechanical problem but can recommend getting a Gripmaster for the trigger finger exercise. I found the black, heavy, model too much and suggest getting a lighter model, perhaps approximating the double action pull weight of your revolver. I have seen Gripmasters with crude plastic gun sights attached that might make for more effective practice in addition to the strength building but none of the owners could cite a source and my casual search failed to locate a vendor. YMMV __________________ Gee, I'd love to see your data!

August 14, 2015, 10:52 PM	#12
Skeets Member in memoriam Join Date: April 6, 2015 Location: Indiana Posts: 583	An S&W armorer told me I was"outrunning"my M34 trigger design.Slowed downed,never happened again.Just a thought... __________________ Skeets "Over Kill Never Fails"

August 15, 2015, 01:48 AM	#13
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	Since tidying up the snap-caps it hasn't happened again but I certainly would not want a trigger design in a carry gun that requires me to slow down!! That gun should be working at my speed, not vice versa!! __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.

August 15, 2015, 04:13 AM	#14
Skeets Member in memoriam Join Date: April 6, 2015 Location: Indiana Posts: 583	Glad your up and running James,Good Shooting! __________________ Skeets "Over Kill Never Fails"

August 15, 2015, 04:31 AM	#15
Pond, James Pond Senior Member Join Date: July 12, 2011 Location: Top of the Baltic stack Posts: 6,079	Don't know about good shooting, but certainly fun!! __________________ When the right to effective self-defence is denied, that right to self-defence which remains is essentially symbolic. Freedom: Please enjoy responsibly.