Ruger NMV Problem

[Kansas City Munny]

Hello Cowboys and Cowgirls. 
 

I’m having an issue with a Ruger NMV. It’s virtually new and the only modifications have been Wolff springs and a SBH hammer. It’s built identical to my main match pair wish are 512-series guns and work perfectly. The problem unit is a 513- series. 
 

So the problem is the hammer is not striking the firing pin with enough force to set off primers. The hammer is stopping in the last 1/32” of travel. The hammer can be pushed all the way forward, but there is resistance. When thumbing the hammer back slightly, this resistance can be felt and the hammer does not return to full rest position against the frame when you let it go. 
 

I’ve had this gun apart 40 times, polished all of the inner parts at the mating surfaces, put the stock hammer back in, tried different hammer springs (still Wolff) and function is always the same. When disassembled partialLy w the internal parts in the frame and grip frame not attached or hammer strut not in, the hammer travels freely with no binding or resistance. 
 

Thoughts? I appreciate any help on this one. 
 

Thanks,

KCM

 

[Larsen E. Pettifogger, SASS #32933]

Check for two things first.  Take the gun apart and examine the spring strut to make sure it is not bent.  They are easy to bend if you try to install the spring while the gun is fully assembled.  Next take out the pawl (aka hand), reassemble the gun and see how the hammer works.  If everything is OK the pawl is not fitted to the grip frame properly.  This is a common problem when you put in iighter springs.  The spring cannot overcome the camming action of the pawl.

 

There is a tail on the pawl.  Photo one.  This tail fits into a groove in the grip frame.  Photo 2.  The poor fit of the tail into the groove is one of the main causes of what you are describing.

 

 

[Kansas City Munny]

Hi Larsen,
 

Now that you mention it, the slot in the grip frame do not look quite right. Like perhaps the pawl is not engaging the slot properly. 
 

I appreciate the feedback and I’ll take it apart again tomorrow and see if I can narrow the problem down. 

Thanks!

Munny

[J-BAR #18287]

The hammer plunger is on the right side of the hammer.  Its job is to raise and lower the cylinder stop(bolt).  Sometimes the plunger drags on the leg of the cylinder stop and needs to be polished, especially if you have light hammer springs.  With heavy factory original hammer springs the problem never shows up.  But who uses factory springs!!  
 

If it is the hammer plunger riding on the bolt that is causing the problem, you can feel the hammer “grab” or hesitate as it falls towards the firing pin/transfer bar.

[Kansas City Munny]

The hammer plungers appear to be working OK and I did try two different hammers, but I’ll look for contact marks when I have it apart again. 
 

Thanks,

KCM

[The Original Lumpy Gritz]

Does it still happen if you remove the cyl?

Make sure the cyl pin is not the issue. 

OLG 

[Kansas City Munny]

Hey OLG,

 

It functions exactly the same with the cylinder and pin removed. 
 

KCM

 

1 hour ago, The Original Lumpy Gritz said:

Does it still happen if you remove the cyl?

Make sure the cyl pin is not the issue. 

OLG 

 

[The Original Lumpy Gritz]

Do you have the hammer strut positioned correctly? 

OLG 

[Rex M Rugers #6621]

I will be watching this thread for info. I have a SBH hammer that does the same thing Kansas City Munny is describing. I have tried it in , I think , 4 different Vaqueros, Two  older 44 mags , and two new Vaqueros. Fortunately I have always had another one to use , so just kept pitching it back into the parts box.

Rex 

[Kansas City Munny]

 

3 hours ago, The Original Lumpy Gritz said:

Does it still happen if you remove the cyl?

Make sure the cyl pin is not the issue. 

OLG 

 

2 hours ago, The Original Lumpy Gritz said:

Do you have the hammer strut positioned correctly? 

OLG 

It is. I’ve literally taken it down to bare parts 50 times and carefully reassembled each time ensuring all parts are in exactly as they should be. 

1 hour ago, Rex M Rugers #6621 said:

I will be watching this thread for info. I have a SBH hammer that does the same thing Kansas City Munny is describing. I have tried it in , I think , 4 different Vaqueros, Two  older 44 mags , and two new Vaqueros. Fortunately I have always had another one to use , so just kept pitching it back into the parts box.

Rex 

Hi Rex,

 

The current condition is the same with the SBH hammer and the original. 
 

KCM

[Dusty Devil Dale]

Does the gun have its transfer bar in place or removed? 

 

1)  If it is in place, the base pin plunger might be bent or frozen in the out position, holding back pressure on the t-bar.  

 

2) With the T-bar out, the hammer face normally has to be modified/built up ---- but I'm sure you know that.   But did it get overlooked in replacing the original hammers with SBH?

[The Original Lumpy Gritz]

Remove the cyl pawl/hand and try it.

OLG 

[Kansas City Munny]

4 hours ago, Rex M Rugers #6621 said:

I will be watching this thread for info. I have a SBH hammer that does the same thing Kansas City Munny is describing. I have tried it in , I think , 4 different Vaqueros, Two  older 44 mags , and two new Vaqueros. Fortunately I have always had another one to use , so just kept pitching it back into the parts box.

Rex 

Hi Rex,

 

The current condition is the same with the SBH hammer and the original. 
 

KCM

58 minutes ago, Dusty Devil Dale said:

Does the gun have its transfer bar in place or removed? 

 

1)  If it is in place, the base pin plunger might be bent or frozen in the out position, holding back pressure on the t-bar.  

 

2) With the T-bar out, the hammer face normally has to be modified/built up ---- but I'm sure you know that.   But did it get overlooked in replacing the original hammers with SBH?

Still running the T-bar. 

[Kansas City Munny]

22 minutes ago, The Original Lumpy Gritz said:

Remove the cyl pawl/hand and try it.

OLG 

With the pawl removed, it functions 100% and drops the hammer all the way. 

[Larsen E. Pettifogger, SASS #32933]

I suggested removing the pawl in the very first post and I told you what causes the problem.  Hopefully you get it fixed.

[The Original Lumpy Gritz]

OP, the tab at the bottom of the pawl, remove .015 in full radius from it.

Try it now with pawl in place....

OLG 

[German Jim]

23 hours ago, Larsen E. Pettifogger, SASS #32933 said:

 

 

There is a tail on the pawl.  Photo one.  This tail fits into a groove in the grip frame.  Photo 2.  The poor fit of the tail into the groove is one of the main causes of what you are describing.

 

 

Larsen, could you just grind off that tail or shorten it up?  Just curious.  Doesn't seem or look like it does anything.  Something like your appendix. 

[Kansas City Munny]

5 hours ago, Larsen E. Pettifogger, SASS #32933 said:

I suggested removing the pawl in the very first post and I told you what causes the problem.  Hopefully you get it fixed.

Hi Larsen,

 

You totally did abc I appreciate the direction. 
 

I’ll see if I can mage to fit the Pawl. 
 

Thanks Again!

KCM

[Larsen E. Pettifogger, SASS #32933]

1 hour ago, German Jim said:

Larsen, could you just grind off that tail or shorten it up?  Just curious.  Doesn't seem or look like it does anything.  Something like your appendix. 

 

On the Vaquero loading and unloading was often difficult because there is no half-cock notch on a Ruger and if the cylinder were rotated just a few degrees to much you could not eject the empty and had to  push the round back in the chamber and rotate the cylinder and try again.  On the New Vaquero Ruger installed the pawl with the tail on it so that the cylinder could rotate backwards and then put the little spring loaded pin in the frame to keep the chambers centered in the loading gate.  This gives the effect of a half-cock notch.  A pawl without a tail sits about like photo one when the hammer is at rest.  As the hammer is falling the tail (photo one) catches in a notch in the top of the gripframe (photo above).  The last 1/8" or so of hammer travel the pivot hole for the pawl actually changes direction and pulls rearward just a bit.  The tail catches in the gripframe and the hammer will pull it to the rear, photo 2, to release it from the ratchet for loading and unloading.  These pawls often need hand fitting to work properly.  On some guns as the hammer spring pressure is reduced the the pawl will push backward on the hammer because of the poor tail to gripframe fit.  The main frames are cast and sometimes things are not to spec.  I have ground the tail off to eliminate problems with poor frame casting.  Basically makes it like a Vaquero (except the frame pin still helps align the cylinder) and makes getting light springs to work easier.  Unless there is a real issue with poor fitting parts I would fit the tail properly as it does make loading and unloading easier.

 

 

[Kansas City Munny]

13 hours ago, Larsen E. Pettifogger, SASS #32933 said:

 

On the Vaquero loading and unloading was often difficult because there is no half-cock notch on a Ruger and if the cylinder were rotated just a few degrees to much you could not eject the empty and had to  push the round back in the chamber and rotate the cylinder and try again.  On the New Vaquero Ruger installed the pawl with the tail on it so that the cylinder could rotate backwards and then put the little spring loaded pin in the frame to keep the chambers centered in the loading gate.  This gives the effect of a half-cock notch.  A pawl without a tail sits about like photo one when the hammer is at rest.  As the hammer is falling the tail (photo one) catches in a notch in the top of the gripframe (photo above).  The last 1/8" or so of hammer travel the pivot hole for the pawl actually changes direction and pulls rearward just a bit.  The tail catches in the gripframe and the hammer will pull it to the rear, photo 2, to release it from the ratchet for loading and unloading.  These pawls often need hand fitting to work properly.  On some guns as the hammer spring pressure is reduced the the pawl will push backward on the hammer because of the poor tail to gripframe fit.  The main frames are cast and sometimes things are not to spec.  I have ground the tail off to eliminate problems with poor frame casting.  Basically makes it like a Vaquero (except the frame pin still helps align the cylinder) and makes getting light springs to work easier.  Unless there is a real issue with poor fitting parts I would fit the tail properly as it does make loading and unloading easier.

 

 

I have removed a small amount of material from the tail, and it's closer to functioning. I've worked on many very complicated weapons, but I'm a little 'gun shy' with this project.  Previously,  I had a problem with a previous pistol and tried fitting the pawl and may have removed too much material or may have not shaped it correctly as the result was the pawl sticking through the window in the frame and stopping the cylinder from rotating when the gate was open. Advice?

[The Rainmaker, SASS #11631]

ALWAYS take material off of the cheaper, easier to obtain piece!

Trim and try, repeat. Little at a time until it works.

You can always take more off... a little harder the other way.

[Larsen E. Pettifogger, SASS #32933]

1 hour ago, Kansas City Munny said:

I have removed a small amount of material from the tail, and it's closer to functioning. I've worked on many very complicated weapons, but I'm a little 'gun shy' with this project.  Previously,  I had a problem with a previous pistol and tried fitting the pawl and may have removed too much material or may have not shaped it correctly as the result was the pawl sticking through the window in the frame and stopping the cylinder from rotating when the gate was open. Advice?

 

Do NOT touch anything other than the tail of the pawl.  Not rocket science.  The worst that can happen is it functions like a normal old style Vaquero.

[Kansas City Munny]

10 minutes ago, Larsen E. Pettifogger, SASS #32933 said:

 

Do NOT touch anything other than the tail of the pawl.  Not rocket science.  The worst that can happen is it functions like a normal old style Vaquero.

The previous one I worked on, I only reduced the tail size and no other portion of the pawl. Still derailed the train..

 

Is there any issue with the shape of the tail being consistent? Maintain the same shape but shorten? No need to trim the side to side dimension so it fits in the grip frame groove?

 

Thanks Larsen!

 

KCM

[Larsen E. Pettifogger, SASS #32933]

1 hour ago, Kansas City Munny said:

I have removed a small amount of material from the tail, and it's closer to functioning. I've worked on many very complicated weapons, but I'm a little 'gun shy' with this project.  Previously,  I had a problem with a previous pistol and tried fitting the pawl and may have removed too much material or may have not shaped it correctly as the result was the pawl sticking through the window in the frame and stopping the cylinder from rotating when the gate was open. Advice?

 

In all honesty I cannot figure out what you are saying.  The pawl has to stick through the window in the frame.  When the cylinder is in place the pawl cannot stick in to far as the ratchet teeth limit how far forward the pawl can move.  If you completely removed the tail you should not have the problem you are describing.  What you are describing sounds more like the bolt is not fully retracting down into the frame.

[Kansas City Munny]

2 minutes ago, Larsen E. Pettifogger, SASS #32933 said:

 

In all honesty I cannot figure out what you are saying.  The pawl has to stick through the window in the frame.  When the cylinder is in place the pawl cannot stick in to far as the ratchet teeth limit how far forward the pawl can move.  If you completely removed the tail you should not have the problem you are describing.  What you are describing sounds more like the bolt is not fully retracting down into the frame.

Gotcha. I'll take it apart again and work the tail slowly until the hammer drops as it should and see how the cylinder functions as well.

[Larsen E. Pettifogger, SASS #32933]

One thing just to make sure.  Are you saying the cylinder won't rotate counterclockwise or won't rotate at all?

[Kansas City Munny]

2 hours ago, Larsen E. Pettifogger, SASS #32933 said:

One thing just to make sure.  Are you saying the cylinder won't rotate counterclockwise or won't rotate at all?

With the pawl I messed with before, the cylinder wont rotate at all.

[Kansas City Munny]

On 9/13/2021 at 9:56 AM, Larsen E. Pettifogger, SASS #32933 said:

One thing just to make sure.  Are you saying the cylinder won't rotate counterclockwise or won't rotate at all?

Larsen,

I received a new pawl and have started trying to fit it. As an experiment, I took one of the old pawls, ground off the tail, smoothed and finished it and installed it. With the spring and plunger forcing the pawl towards the cylinder and no tail to ride in the grip frame, the result is the same. The pawl protrudes through the frame and locks the cylinder up completely. 
When working the new pawl, I’m concerned the same condition will occur. I’m using a stone and 800-2000 grit sandpaper and taking very little off at a time and reassembling. So far, the hammer does not fall all the way. What a PITA. 

[The Original Lumpy Gritz]

OP, take your stone and put a small flat spot on the inside edge tip of both ledges on the pawl. 

Are you sure, the cylinder stop is not causing interference? 

OLG 

[Kansas City Munny]

3 hours ago, The Original Lumpy Gritz said:

OP, take your stone and put a small flat spot on the inside edge tip of both ledges on the pawl. 

Are you sure, the cylinder stop is not causing interference? 

OLG 

OLG,

The cylinder stop looks to be functioning normally. Fully assembled, the pistol is working normally with the exception of the hammer not falling all the way. The hammer does fall to rest when the trigger is released. Also hammer operates normally with no pawl installed. 
I’m guessing I need to take more off the tail of the pawl. 
When you suggest a flat spot on the inside edge, are you referring to the tail of the pawl?

[The Original Lumpy Gritz]

46 minutes ago, Kansas City Munny said:

OLG,

The cylinder stop looks to be functioning normally. Fully assembled, the pistol is working normally with the exception of the hammer not falling all the way. The hammer does fall to rest when the trigger is released. Also hammer operates normally with no pawl installed. 
I’m guessing I need to take more off the tail of the pawl. 
When you suggest a flat spot on the inside edge, are you referring to the tail of the pawl?

My post was about the rotation issues of the cly.

I'm referring to the 2 'steps' on the pawl that engage the cyl ratchets. 

OLG 

[Kansas City Munny]

17 hours ago, The Original Lumpy Gritz said:

My post was about the rotation issues of the cly.

I'm referring to the 2 'steps' on the pawl that engage the cyl ratchets. 

OLG 

Gotcha. I have not touched the steps at all.