I purchased the Crimson Trace LG-359 Lasergrips for my S&W 4006.

Tested the grips prior to installation; worked fine.

As soon as grips were installed on the gun; it would not light.

Contacted Crimson Trace and they asked if it was a stainless steel gun; and sent out a new grip.

Same issue; grip works right up to placing on gun.

Returned the grips.

Crimson Trace did not have an answer for what was occurring.

Anyone else have this problem?

Laser Sight for Smith & Wesson 3rd Gen Double-Stack | Crimson Trace

I modified a *bunch* of these LG359's to fit compact models and they are just dirt simple and not much can go wrong with them. I'm sure you tried moving the master switch on the butt, perhaps it got bumped during installation. Does the laser work again after you remove it from the pistol?

Switch did not get bumped. Yes I tried turning it on/off with grip on gun; did not work.

Yes, as soon as I removed the grip from the gun the laser sight came on...

With the grips off the gun (and the laser working), did you try flexing and squeezing the grips? There's the circuit board and the flat connector cable that could have an open circuit when squeezed a certain way. But you said it has happened with two different grips so that doesn't make any sense.

I've modified more of these grips than I can count and each one was test fit dozens of times and I've never run in to anything like this.

Let us know if you figure it out.

It was as if the laser shorted out once the grips were placed on the gun.

If Crimson Trace comes up with anything...