Knew I'd have to explain it to you so here goes, the thread is about the bolt and the bolt is what they mark MPI, the extractor and spring is part of this bolt so if one part is junk, like Blue said about the extractor spring, chances are good the rest of the parts are junk too. Though they could still mark it MPI, It, meaning the bolt, which is part of the bolt carrier group, though the bolt is the only part they test and mark but some companies only batch test so not all their marked bolts are really tested and while we're at it, unless they HPT before they MPI, they are waisting their time.
Try and keep up.
BCG is bolt carrier group.
Ahh yes, 1 spring failing for what ever reason is evidence of everything being wrong and the whole thing should be scrapped. Car dealers in both of your areas probably dick with your windshield wipers and tire pressure so you will come in for a trade(massive loss on your side) out of pure disgust with the faulty equipment.
Are you sure you need to explain anything to anyone considering that issue and your failed attempt at letting us know what they are doing with time?
