Like the title says, I'm looking at a used M&P 40 pro, 5" barrel. It seems that S&W has changed a number of things in the trigger and other items on these guns over time. Is there anything I should check for? After what year would most of the newer improvements be in place?

Also, if I decide to go all-out with a full Apex trigger set, how much do the S&W improvements matter, will all of that be taken care of with the aftermarket parts?

The most important thing I would look for is overall condition. If it looks like it has been dragged behind a car, I would pass.

From my perspective, if you're looking at a previously owned S&W one big consideration is that you don't get the lifetime warranty you would with a new gun, so the price needs to be significantly lower than new. What's significant? That is up to you.

I put the Apex Duty/Carry kit in my 5" Pro using the stock spring and from my perspective it is just about perfect for home defense or casual competition. It will go well beyond rectifying trigger issues that the factory may have diddled with over time.

Otherwise, as pyro said, overall condition; does the gun look like it has been cared for? Is it clean? Is it lubricated? If I was going to sell a gun, I'd clean it before showing it. I think most people you'd want to buy a gun from would do the same.

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Jim - M&P Pro 40L/Shield 40