Anything mechanical has a failure rate, what are the most commonly replaced worn parts on the AR15 platform (S&W M&P), what would be reasonable to try and acquire to make sure the one I own lives forever.
Obviously two of everything on it would be grand, but now likely more like 3 grand...
I would just like to know if something breaks I have one in my closet, not have to scour the web after the fact.
Any resources on duty cycles on the individual parts would be great.
Thanks in advance.