They're made to military spec. They're different manufacturers, but the part ius made the way it is supposed to be made. Other makers don't MPI and shot peen it, because that is not something you can see, adds a small chance of failure into the equation, and costs a decent chunk of change. This enables them to sell the part cheaper and have less rejects, which means more sales and more $$$.
To be fair, you can have a non-MPI'ed, non shot-peened bolt and have it run like a top and outlive you. The chances of this happening go up and up the less and less you shoot your rifle, since if the part is fine it will be fine regardless, and if the part has a hidden flaw it will still be fine if it is not stressed (read: not shot much). Inversely, the chances of this happening go down as you shoot more, since a part that has a hidden flaw is more likely to fail the more often you shoot it.
MPI is Magnetic Particle Inspection. basically, the bolt is examined for hidden microscopic flaws. If the bolt has these flaws, it is likely to fail unacceptably early in its service life. MPI'ing the bolt weeds out bolts that are more likely to fail. This is a Good Thing. Failing to MPI the bolt will not matter one bit if the bolt is good, but might matter if it is not.
Heat treating is just a metal-working technique that ensure that the metal has the right strength and flexibility. Get it wrong and the metal will be either too hard/brittle or too soft/pliable.
Shot-peening is a technique that increases the strength of the metal in the bolt. Basically it is like sand or bead blasting.
Mike
). If answering my questions is too much or a waste of time, don't bother. There are plenty of other people willing to spread knowledge. If I was asking questions that had a repeated answer, the 3 moderators would have pointed me to it and told me to shaddap.
