11-29-2017, 12:03 PM
http://demigodllc.com/articles/the-armal...try-rifle/
I was reading this article (link above) on ArmaLites modern take on the A2 platform, and saw this point about the bolt design:
The AR-15 bolt can be thought of as starting with eight lugs around its circumference. One is cut away to provide room for the extractor. During firing, this asymmetry causes the bolt to warp slightly due to uneven support and put approximately 80% of the force load on the two lugs adjacent to the extractor. It's no surprise that the majority of bolt lug failures occur at one of these two lugs.
ArmaLite's solution is to balance the force by only using six of the seven lugs for load-bearing, restoring symmetry under load. This change is accomplished by simply shortening the back of the lug opposite the extractor so it does not engage the barrel extension. ArmaLite's engineering study determined that this change alone reduces the stress on the two problem lugs by about 40%.
Seeing as the Grendel already has an ongoing debate on bolt face depth and reliability, I was hoping to hear some of your opinions from a technical standpoint.
I was reading this article (link above) on ArmaLites modern take on the A2 platform, and saw this point about the bolt design:
Quote: Like any machine, the AR-15 has some parts that will eventually wear out. The bolt is one of these, contributing to both infant mortality failures and long-term failures for bolts with over 10,000 rounds. These failures usually involve cracks developing at the base of the two lugs adjacent to the extractor or at the cam pin hole causing the bolt to eventually break.
The AR-15 bolt can be thought of as starting with eight lugs around its circumference. One is cut away to provide room for the extractor. During firing, this asymmetry causes the bolt to warp slightly due to uneven support and put approximately 80% of the force load on the two lugs adjacent to the extractor. It's no surprise that the majority of bolt lug failures occur at one of these two lugs.
ArmaLite's solution is to balance the force by only using six of the seven lugs for load-bearing, restoring symmetry under load. This change is accomplished by simply shortening the back of the lug opposite the extractor so it does not engage the barrel extension. ArmaLite's engineering study determined that this change alone reduces the stress on the two problem lugs by about 40%.
Seeing as the Grendel already has an ongoing debate on bolt face depth and reliability, I was hoping to hear some of your opinions from a technical standpoint.
-Zac
Husband, Father, Veteran. Grateful for my redemption.
Husband, Father, Veteran. Grateful for my redemption.