GUNSMITHING SERVICES: AR-15 Extractor installation to M700 Bolt
The AR-15 Extractor installation to an M700 bolt has become a very popular and almost required upgrade for a number of applications. The factory extractor is good. Very good-right up to the point that it isn't. When working with magnum bolt face cartridges, the AR-15 extractor is almost a must have as the riveted factory piece is known to be problematic.
LRI starts this process a little differently. A close inspection of a factory M700 bolt will show a number of intricate machined features where the factory extractor resides. These features can have a detrimental effect on the operation of the rifle with the an AR-15 extractor.
Because of this, the first thing we do is fit a bushing to the bolt face. Our bushings are soldered for a permanent installation. We are strongly opposed to the use of epoxy for bushing retention. In the event of a violent case rupture, the bushing can also fail. This process begins in our Harding HLV toolroom lathe.
The ID of the bolt face is enlarged to make room for the bushing. Micro grooves are machined on both the bushing and the bolt face ID for solder to flow into, creating a mechanical lock to ensure the bushing never comes loose.
Concerns about annealing/damaging the bolt head due to excessive heat exposure are answered by submerging the bolt body in a tank of water. Water is one of the most efficient ways to manage heat. Hardness and toughness specifications are preserved while ensuring a permanent bond.
Next is doing away with open flame. Instead we use magnetic induction to do the work. Avoiding an open flame means the risk of carburizing the machined features is almost eliminated. Induction also heats more evenly and with the high power it does the job very quickly. This is critical to mitigate thermal transfer to the lug and bolt face features.
Once installed the bushing is finish machined to a clean presentation. The extractor fitting is performed on dedicated fixtures in one of our Kitamura machining centers. With the exceptional repeatability and accuracy of these machines, it ensures reliable function with neat, clean presentation.
We didn't stop there. A variety of companies are making the extractor. Within that community exists small, yet important differences. None are really better than the other, however it does require one to be "on the ball" so that the appropriate program is loaded in the machine. This is complication that leads to mistakes. Our solution was to start making our own.
The LRI M16 extractor is compatible for both .480 and .545 bolt face cartridges. -.308 and Standard Magnum. It is 100% machined from chromoly bar stock. The existing extractor design is quite good. We didn't make the effort to reinvent any wheels. That said, some small changes were made. The claw feature now has a .005" radius to mitigate abuse to the case rim. Additionally, radius features were substituted on the pin boss rather than the conventional 45* chamfer.
The outside radius is surface machined rather than contoured. Takes a little longer to do, but it simplified the work holding. Last, we added our logo.
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