I am looking to pick up a few spare parts for my 1.0 Shields in 9mm and .40 as well as for my full size 1.0 in .40. My question is are the trigger return springs the same? Also, any suggestions for other spare parts to have on hand is greatly appreciated. Thanks for your help.

I see that nobody have answered your question. But according to the parts price list on the M&P models that I got from S&W, the trigger return spring is the same on all the M&P models, both 1st and 2nd generation, except the Bodyguard and EZ models.
The SKU is 391420000

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Hello darknes my old friend

As for other parts to have on hand just in case something breaks, the M&P pistol armorer manual have the following service interval.

At 5000 rounds replace:

• Slide stop
• Trigger return spring
• Recoil spring assembly
• Magazine spring and follower

At 10 000 rounds replace

• Slide stop
• Trigger return spring
• Trigger bar assembly
• Recoil spring assembly
• Striker assembly
• Magazine spring and follower

At 15 000 rounds replace:

• Slide stop
• Trigger return spring
• Recoil spring assembly
• Magazine spring and follower

At 20 000 rounds replace:

• Slide stop
• Trigger return spring
• Trigger bar assembly
• Recoil spring assembly
• Locking block assembly
• Locking block assembly
• Magazine catch
• Striker assembly
• Striker block, spring and spacer
• Magazine spring and follower
• Ejector

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Hello darknes my old friend