SW41 trigger problem with aftermarket grips

I have a puzzling problem with my 41 that only happens with aftermarket grips.  With the factory grips it functions well, but with now two different aftermarket grips (Herritt?) there is an intermittent trigger issue. 

The problem: sometimes while activating the trigger, part way through the travel there is a click but no hammer drop or fire.  At this point the trigger can't be pulled back further, but if let up and re-pulled, the hammer drops and the gun fires.  It is intermittent, but often enough to make the grips unuseable.

Comparing the aftermarket with factory grips, the inside of the grips that abuts the frame is more precisely milled on the factory grips and the shapes of the cut-outs are different.  I suspected that the there must be one or more spots on aftermarket grips that interfere with the trigger action, so I ground away wood on the aftermarkets to create clearance for any moving parts.  But so far this hasn't worked.

Here is a photo of the right side of the 41 and the inner surfaces of the grips that fit on the right (factory grip has "4" milled in).   The linkages on the pistol just below the slide and "Smith and Wesson" move when the trigger cycles, and on the factory grip the wood is milled away over these linkages.   The red circles show some of the differences in milled areas on the aftermarket grip, which I ground out to avoid contact with the linkages - but it still malfunctions.  (I ground enough to see the linkages when the gun is assembled and they are clear).  I also relieved where the hammer spring/bar rides at the back of the frame.

https://postimg.cc/94RBGyjG

Here is left side of the gun and grips, showing areas I relieved to clear the spring, slide latch, and safety (the safety spring was modified to stiffen the safety, so this is not the problem)

https://postimg.cc/SJS3c11C

Any suggestions?  Thanks very much in advance

Are you certain your hand isn't riding just a little higher with the new grips and contacting the safety enough to nudge it?

THank you Ed.  I don't think it is the safety though.  Previously* I kinked the spring so that activating the safety takes a lot of force, and in any case it is quite far from my thumb:   https://postimg.cc/H8rtY5sZ

*one of many past trials and tribulations with the 41 led to this mod.  The safety used to get bumped during firing with the factory grips, but this never happens now that I fixed the spring

One other difference is the factory grips have two steel indexing pins where the grip-halves meet.  This appears to index the grips to each other, and along with the more precise milling, hold more solidly to the frame than the aftermarket grips.

Look at the raised portion on the lower left of the trigger bar.  Is that a bright spot form rubbing on the grip? (Left notch holding the clip spring for the bar).

Here?  I checked under magnification and it does not appear to be worn.  I did worry about this area, however, and relieved the grip alongside the trigger bar.

https://postimg.cc/YjQB6yNC

Here is the same area with the factory grip in place

https://postimg.cc/tsDsXNB9

I just noticed something else.  There is a rounded pin above and behind the trigger.  The after-market grip covers and contacts it, but the factory grips are clear:

Factory grip:  https://postimg.cc/p9sR72PZ

Aftermarket:  https://postimg.cc/ykspJ0mD

What does this pin do?  Would pressure on this pin affect trigger function?

The right-side Herrett grip has an area top left at the front of the cutaway area where the raised bumps on the trigger bar have been rubbing the grip:



When you squeeze the trigger, the z-shaped trigger bar above and to the rear of the trigger moves to actuate the sear.

Excellent catch!  I will relieve this too.

JHHolliday wrote:I just noticed something else.  There is a rounded pin above and behind the trigger.  The after-market grip covers and contacts it, but the factory grips are clear:

Factory grip:  https://postimg.cc/p9sR72PZ

Aftermarket:  https://postimg.cc/ykspJ0mD

What does this pin do?  Would pressure on this pin affect trigger function?

IIRC that pin holds the stepped ramp in place that adjusts trigger spring pressure.  Contact with that pin should do nothing to pistol function.

JHHolliday wrote:Excellent catch!  I will relieve this too.

Pretty sure that is what CR10X was talking about also.

Looking closer I don't think that pin matters because it doesn't move during triggering.  However this pin - which I think the hammer pivots on - does rotate during triggering:

https://postimg.cc/7CZfbt6K

AND it contacts the aftermarket grip: here marked by inking the pin and dry firing with the grip in place

https://postimg.cc/2bBjBsf7

I will relieve this area and report back

PS I checked, and the "z shaped bar" on the right does not contact the grip.  The wear spot on the wood is not over the bar or any moving parts nearby

I relieved the areas of the grip that contacted the hammer pin and will re-assemble for dry fire testing

https://postimg.cc/qNk5h2dm

Also check your over travel.

Thanks KC.  Do you mean the over-travel stop screw at the back of the trigger guard?  The trigger moves about 1mm from the break until it hits the screw.

Is over-travel affected by some area of the grips?

Yes I was talking about the screw in the receiver behind the trigger.  And no over travel would not be affected by aftermarket grips.

Got to the range today and had the same problem with the aftermarket grips: trigger click part way through travel, no fire, then sometimes firing when letting off and re-triggering.  Changed to the factory grips and the problem vanished.

Any other suggestions?

Thanks

JHHolliday wrote:Got to the range today and had the same problem with the aftermarket grips: trigger click part way through travel, no fire, then sometimes firing when letting off and re-triggering.  Changed to the factory grips and the problem vanished.

Any other suggestions?

Thanks

I am unfamiliar with this pistol, but I would clean/ degrease the grips. Then apply some grease  to all of the moving parts that have any chance of contacting the grips, cycle the gun then disassemble and check for grease  on the grips. then clearance as needed.