Mausingfield Toroidal Locking Lugs HD

Ted Karagias, President of American Rifle Company informs viewers about the locking lugs of the Mausingfield bolt action. The Mausingfield bolt has two diametrically opposed locking lugs that do not need to be lapped, ever. This feature is so important that it warrants an explanation. Inherent to virtually all other bolt guns is an interaction between the firing pin and the sear that forces the bolt out of alignment with the receiver causing the locking-lugs to disengage the receiver when the bolt is closed. Because the bearing surfaces of both the lugs and the receiver are flat, any misalignment between the bolt and receiver must necessarily separate these surfaces. The lugs ultimately come to bear against the receiver when the rifle is fired, but not without excessive movement of the bolt within the receiver. This movement is detrimental to accuracy and in order to prevent it, gunsmiths lap the locking lugs against the receiver to ensure that the two are contacting one another when the bolt is closed. Shortcomings in design make this laborious task necessary. In stark contrast to its competitors, the bearing surfaces within the Mausingfield are designed to properly engage one another when the bolt is closed, regardless of the alignment between the bolt and the receiver. The bearing surfaces of the locking lugs are shaped as portions of a torus and bear against surfaces within the receiver that are shaped as portions of a sphere. Regardless of the alignment between the bolt and the receiver, the respective bearing surfaces maintain contact, in this case along arcs that bisect the bearing surfaces of the lugs. Under load, both bearing surfaces are uniformly and elastically flattened against one another, enabling proper load sharing between the lugs, thus increasing the load bearing capacity of the breech. The contact between the Mausingfield locking lugs and receiver is, by design, insensitive to the alignment between the bolt and the receiver, thereby making lapping unnecessary.