A set of back up parts.

[sonyman74]

If you was to assemble a set of back up parts. What would those be?  And where would be the best place to get said parts?

[StrangerDanger]

Rubber o-rings, pistons, springs, pins, maybe assembly groups like a spare trigger pack or bolt carrier group. 
 

Brownells sells a lot of these parts, but they’re not cheap. Things like trigger packs and bolt carrier groups will send you into a seizure when you see the price. If deciding to build another trigger pack, I’d fit an aftermarket one the way you like. Then piece the oem parts you’ve removed into its own assembly. 

[MNtadpole]

I personally own a whole trigger group assembly in hot standby as backup. I want to get an additional firing pin.

[NoTycoon]

The parts that have broken on me and that I now carry spares for are: Carrier Latch and Bolt Handle.

 

[Birdog19]

Agree with Tycoon on the low end of the affordable spares package!  Along with those 2 items I carry spare pins and the trigger guard pin spring (018J) as Benelli calls it; otherwise referred to as the trigger pin bushing retaining spring clamp.  Not a bad idea to package up all your small OEM parts and carry them as spares as well.