NOTE: Gunsmithing Services are invasive and will most often (directly with tooling or indirectly with work holding) damage existing surface finishes on parts such as receivers. LRI offers a full menu of finish options for your components, please ensure you have also added an appropriate finish option to your cart if applicable.
Finish Options
Cerakote (most popular)Parkerize Carbon Steel Action
Parkerize Carbon Steel Bolt
Glass Bead Stainless
GUNSMITHING SERVICES: 8-40 base hole receiver threading
An unfortunate side effect of production-grade receivers is the tendency for certain features to be machined slightly out of position. Our 8-40 optic base hole upgrade is intended to resolve this issue, additionally, it can also add base holes to receivers that were not originally machined for them. (1903 Spgfld, Mauser, etc...)
By aligning the receiver bore parallel to the machine's work environment, we can correct positional errors on existing holes already in the receiver. The traditional process is to chase the existing holes with a drill and complete the job by tapping to the 8-40 thread pitch size.
LRI does not follow the drill/tap process. Instead, we bore the existing holes to size using an endmill. Doing so ensures that the bore center is truly at the desired location. Drills struggle to correct a positional error of an existing hole.
Boring ensures ensures both the location and size. Next, we use Thread Milling to machine the threads that the fastener will engage with.
The end result are optic bases that are parallel to the receiver bore. This reduces windage errors, allows optics to remain closer to their mechanical center point, and ensures that bases clamp to the receiver correctly.
This service is offered in two ways. One is a stand-alone where this is all we do. The 2nd is as an elective to our accurizing service. The setup work is where the majority of the cost originates from. The same procedure for base hole work is used to accurize the action as it is the only way to ensure we get it right.
The two different price schedules reflect the setup work involved.
This video shows segments of the thread milling operation:
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