Mine is heavy I'm told by a guy that has one that it is not excessive but tried to measure it with a trigger pull guage Lyman I believe that was meant for rifle trigger pull. It goes up to 8 lbs and it bottomed out and didn't even move the trigger. I'd like it to have around 6-8 lb pull I'm not sure. How would be the best to proceed on this or not at all. Springs or other internal work. sear, ect.

8 lbs is pretty light of a trigger for a CCW, however if you wanted to do this I'm not sure you would even be able to and still get the reliability out of the gun you would want. I would dry fire it a few thousand times, and build up the strength in your fingers, that will help a lot while also smoothing out the action.

I had a fairly heavy pull on mine until I pulled the side plate off, cleaned it with brake cleaner, then lubed it up, and dry fired it to circulate the new oil.

Yours may be nasty on the inside. Have you checked the internals?

I've found that I can usually get a trigger on any of the Centennial designs down to around 8-9 lbs. and still have 100% reliability. 10 lbs. is almost always attainable, and is typically at least 2-3 lbs. lighter than factory. You'll need to replace at least the rebound slide spring, and likely the mainspring, with Wolff reduced power replacements. I usually use the 13 lb. rebound slide spring. While the sideplate is off, some judicious stoning of contact surfaces will make a lot of difference in smoothness of the pull, making it feel even lighter than it is. If you don't know your way around the innards of a Smith, get it to someone who does, or get a Kuhnhausen manual and Jerry Miculek's video and spend some study time.

I'd say that typically, the 640-1's I've encountered have been among the best D/A triggers I've ever shot. Not that there can't be a clinker in the bunch? But I'll betcha' following the advice above, she'll start to shine! That is a wonderful little gun!

My 640-1 is so smooth and light I thought at first I'd have misfires,but I don't.It's the best DA trigger I've ever had.

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Smooth is always better than light. I recommend sending it to S&W for a Master Revolver Action Package. That would have the added benefit of them fixing anything that is wrong (if there is) while it is there.

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Centennial Every Day