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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Any interest in the Mausingfield?
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<blockquote data-quote="bruce_ventura" data-source="post: 1094101" data-attributes="member: 34084"><p>Not being an expert, I also wondered about the variable bolt alignment. I thought about it a while and came to the conclusion that it might help, but it might also hurt. I looked at the specs for some other custom actions. According to the website, Stiller actions have about .005" diameter (I assume) clearance between the bolt and receiver, for example. For some others the clearance is smaller, around .0025". In all actions, the bolt needs clearance so that it can cycle without jamming if it gets dirty. I suspect that factory rifles tend to have a larger clearance. For benchrest rifles, the clearance can be smaller because the actions are kept clean. For hunting and tactical rifles, however, it's preferable to have a larger rather than smaller clearance. </p><p></p><p>Yes, the Mausingfield lug design allows the bolt to tip and tilt - that's the design feature that enables switching calibers so easily. As machined, the bolt clearance is .012" in diameter, or .006" radially - apparently larger than Stiller actions. The receiver finish reduces this clearance to about .005" radially. </p><p></p><p>On most actions, when the bolt closes, the sear tends to load the striker upward, pushing the rear of the bolt against the top of the receiver and increasing the clearance at the bottom of the receiver. In an action with a .005" radial clearance, this bolt inclination tips the bolt face about .0005". This misalignment is common in most rifles to some degree. How much does it affect rifle dispersion? I would expect it to have some effect, but not a large one, given the elastic deformation of the case at ~60,000 psi. I could be wrong, though.</p><p></p><p>In most actions, the top lug also lifts off the receiver by about .0003-.0007", depending on the clearance. When the gun fires, the load on the lugs is uneven. That's why the lugs on many actions are lapped under tension - to maintain contact on both lugs. But lapping doesn't work very well for multi-caliber rifles. Apparently, the bolt face can also move laterally +/- .002-.005". Consequently, the loading on the lugs and the lateral motion of the bolt face will be slightly different shot to shot. Again, how much this variation affects dispersion is unclear to me, but I suspect it is a significant factor. This is the issue that the Mausingfield lug design overcomes.</p><p></p><p>In the Mausingfield, the toroidal lugs stay in full contact when the bolt closes, so the bolt alignment and position are always the same when the gun fires. The contact and loading on the lugs is always symmetrical. Bolt alignment is the same shot to shot. The fact that the lugs allow the bolt to tip freely is actually a feature that improves reproducibility shot to shot. Whether or not this feature improves dispersion remains to be seen. </p><p></p><p>I don't know how the stress on the Mausingfield receiver during gunfire differs from that of a receiver with flat lugs. I could argue either way - higher or lower or lower stress. In these cases, I would only trust a finite element analysis to answer that question. I think that is a minor issue, though, because the failure tests on the Mausingfield indicate that the receiver is plenty strong enough. </p><p></p><p>Frankly, I think the toroidal lug design is quite clever, but then I'm a gear-headed inventor myself, so what excites me may not be of interest to most people. I suspect that the design might benefit from having bolt to receiver clearance reduced somewhat. The more I think about it, the more I'm leaning toward the Mausingfield for my next rifle build. I really like the idea of switching calibers easily.</p></blockquote><p></p>
[QUOTE="bruce_ventura, post: 1094101, member: 34084"] Not being an expert, I also wondered about the variable bolt alignment. I thought about it a while and came to the conclusion that it might help, but it might also hurt. I looked at the specs for some other custom actions. According to the website, Stiller actions have about .005" diameter (I assume) clearance between the bolt and receiver, for example. For some others the clearance is smaller, around .0025". In all actions, the bolt needs clearance so that it can cycle without jamming if it gets dirty. I suspect that factory rifles tend to have a larger clearance. For benchrest rifles, the clearance can be smaller because the actions are kept clean. For hunting and tactical rifles, however, it's preferable to have a larger rather than smaller clearance. Yes, the Mausingfield lug design allows the bolt to tip and tilt - that’s the design feature that enables switching calibers so easily. As machined, the bolt clearance is .012” in diameter, or .006” radially - apparently larger than Stiller actions. The receiver finish reduces this clearance to about .005" radially. On most actions, when the bolt closes, the sear tends to load the striker upward, pushing the rear of the bolt against the top of the receiver and increasing the clearance at the bottom of the receiver. In an action with a .005” radial clearance, this bolt inclination tips the bolt face about .0005”. This misalignment is common in most rifles to some degree. How much does it affect rifle dispersion? I would expect it to have some effect, but not a large one, given the elastic deformation of the case at ~60,000 psi. I could be wrong, though. In most actions, the top lug also lifts off the receiver by about .0003-.0007", depending on the clearance. When the gun fires, the load on the lugs is uneven. That’s why the lugs on many actions are lapped under tension - to maintain contact on both lugs. But lapping doesn’t work very well for multi-caliber rifles. Apparently, the bolt face can also move laterally +/- .002-.005”. Consequently, the loading on the lugs and the lateral motion of the bolt face will be slightly different shot to shot. Again, how much this variation affects dispersion is unclear to me, but I suspect it is a significant factor. This is the issue that the Mausingfield lug design overcomes. In the Mausingfield, the toroidal lugs stay in full contact when the bolt closes, so the bolt alignment and position are always the same when the gun fires. The contact and loading on the lugs is always symmetrical. Bolt alignment is the same shot to shot. The fact that the lugs allow the bolt to tip freely is actually a feature that improves reproducibility shot to shot. Whether or not this feature improves dispersion remains to be seen. I don’t know how the stress on the Mausingfield receiver during gunfire differs from that of a receiver with flat lugs. I could argue either way - higher or lower or lower stress. In these cases, I would only trust a finite element analysis to answer that question. I think that is a minor issue, though, because the failure tests on the Mausingfield indicate that the receiver is plenty strong enough. Frankly, I think the toroidal lug design is quite clever, but then I’m a gear-headed inventor myself, so what excites me may not be of interest to most people. I suspect that the design might benefit from having bolt to receiver clearance reduced somewhat. The more I think about it, the more I’m leaning toward the Mausingfield for my next rifle build. I really like the idea of switching calibers easily. [/QUOTE]
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Any interest in the Mausingfield?
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