Spare Parts Kit

[briflemn762]

Hey guys, I have lots of experience with the M-1, M-14/M1A and AR-15/M-16 platforms but I've figured out that despite appearances, the AR-10/LR-308 platform is a whole different ballgame from the AR-15.  I understand that a lot of parts I'd expect to be interchangeable, aren't.  My question is, what would you consider to be a reasonable spare parts kit to carry to the range or on a hunt to fix things that commonly break, or are easily lost during routine (or, oops, fell in the creek) break down and cleaning?  I've already managed to break the darned firing pin retaining pin trying to reinsert it.  That's already on my list along with a spare extractor/spring/pin.  Would you recommend OEM or aftermarket parts & why?

 

The rifle in question is  DPMS LR-308 Sporticle that's still in the barrel break-n process.

 

 

It's wearing a Mag-Pul AR-15 forend and buttstock, a no-name (that I can remember anyway) AR-15 grip and a Burris Fullfield II 3-9-40 with a Ballistic Plex reticle & hunter knobs.