I recently acquired a new bolt for my SIG522, which seems to have some small differences compared to the bolt that came with the rifle.
The new one has a matt finish, whereas the original one was polished.
Unfortunately I don't have any pictures of the original bolt prior to the rifle being used, but I have some pictures of the bolt after it had been used to fire around 4000 rounds.
The thing that interests me is the underside of the bolt, near the firing pin. There is a depressed area which corresponds to the part of the bolt which contacts the hammer on recoil, to reset the hammer. See here the arrowed area:
And another view from a different angle:
That bolt surface may have been like that from the beginning, but it has wear on it that is not from the factory. The edge of the shallow area has a burr to it, so it may have been made more pronounced with use.
Now compare that bolt to the new one (and this time I have been smart enough to photograph it before even one round is fired):
It has no depression where the hammer gets contacted for reset.
I have questions:
1) Were the original bolts designed with a recessed area as in my first picture?
2) If they were, what made SIG change this design?
3) If they were not (in other words if the bolts both looked like the third picture when new) is this evidence that the original bolt has not been hardened properly?
I ask this because I can't perceive that amount of wear happening after only 4000 rounds.
The new one has a matt finish, whereas the original one was polished.
Unfortunately I don't have any pictures of the original bolt prior to the rifle being used, but I have some pictures of the bolt after it had been used to fire around 4000 rounds.
The thing that interests me is the underside of the bolt, near the firing pin. There is a depressed area which corresponds to the part of the bolt which contacts the hammer on recoil, to reset the hammer. See here the arrowed area:
And another view from a different angle:
That bolt surface may have been like that from the beginning, but it has wear on it that is not from the factory. The edge of the shallow area has a burr to it, so it may have been made more pronounced with use.
Now compare that bolt to the new one (and this time I have been smart enough to photograph it before even one round is fired):
It has no depression where the hammer gets contacted for reset.
I have questions:
1) Were the original bolts designed with a recessed area as in my first picture?
2) If they were, what made SIG change this design?
3) If they were not (in other words if the bolts both looked like the third picture when new) is this evidence that the original bolt has not been hardened properly?
I ask this because I can't perceive that amount of wear happening after only 4000 rounds.
