Although I've owned an M&P for a few years, I recently decided that my M&P9 would play a more important role in my daily defense. For this and a whole host of other reasons, I would like to collect a basic supply of spare parts to have on hand.

I would like your suggestions of what you think those key and/or critical parts would be and if there is a need to have more than one in a spares kit.

Are there any key tools that a M&P owner would want to add to the spares kit?

Do you have any recommended sources?

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AndrewX
S&W 624, 617 & M&P9

The M&P is a really simple pistol that don’t need many tools, in an emergency you can use the palmswell grip retaining pin as a punch and a magazine as a hammer. But the tools you need to completely disassemble an M&P are.
- 1/16” Allen wrench
- #2 (5/64”) roll pin punch
- #3 (3/32”) solid pin punch
- 1/16” solid pin punch
- Flat head screwdriver
- Brass punch
- Small armorer hammer.
All the tools you can get from Brownells

As for spare parts, the only part that I have seen break from heavy use is the slide stop. But what I see as a bare minimum of must have spare parts are:
- Slide stop
- Striker assembly
- Trigger return spring
- If you shoot ammo with steel case I would also have spare extractor

But to give you and idea of what Smith & Wesson thinks. For M&P pistols that are issued as a service pistol, the service interval and component replacement is as follows:

For every 5000 rounds:
- Slide stop
- Trigger return spring
- Recoil spring assembly
- Magazine spring and follower

For every 10 000 rounds:
- Trigger bar assembly
- Striker assembly

For every 20 000 rounds:
- Locking block assembly
- Magazine catch
- Striker block, spring and spacer
- Ejector

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Hello darknes my old friend

If you maintain M&P well, there is nothing really more to replace than:
- recoil assembly
- striker assembly
- trigger return spring
- sear spring
- magazine spring / follower

Of course all other parts may need to be eventually replaced, as VikingDude posted, but I'm not sure if you really need to keep them ready on you all the time.

Everything is available here:
Smith & Wesson Parts
(this is my favourite M&P part supplier)

With any gun, I think it's prudent to have, in addition to the official wear parts, all the small parts, screws, pins and springs that will inevitably disappear into the carpet and crevices, never to be seen again until you later have at least 3 or 4 more brand new ones on hand.

Just buy another. You have spare parts and extra mags.

A spare barrel? I haven't seen anybody mention that.

Yeah... Everyone needs a spare barrel as a 'Throw Down', so ballistics can't match a suspect slug to your pistol.