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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
steel base and aluminum rings issues?
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<blockquote data-quote="westcliffe01" data-source="post: 530051" data-attributes="member: 35183"><p>rcdinaz, there are a very small number of materials with tailored expansion coefficients. These are the special steels used to mount glass on space vehicles and "high end" jets that need reliable glass to metal seals (blackbird, B1 etc). It is also used for very precise optical assemblies where the sun may strike one side of the assembly and not the other, yet still stay in alignment (in space the temperature difference is quite extreme). Typically, it is Invar and Kovar that are used, together with fused silica (very low expansion glass). I have used these materials in the lab, where we make very precise measurements from ambient to 1000C and the measurement error at 1000C is only about 0.002" from the expansion of the fused silica (at 1000C) and the invar support (at about 90C).</p><p></p><p>With rifles, the problem is not so exotic, since the action is made from either a low alloy steel, or typically 416 stainless steel. Now and again, you find someone using 17-4ph. If it is a custom action, get the scope rail machined into the receiver. If not, pick a rail with the most similar material to the action.</p><p></p><p>With aluminum, both A356 (popular cast material) as well as 6061 T6 have an expansion coefficient close to 25 (metric) so it is what it is....</p></blockquote><p></p>
[QUOTE="westcliffe01, post: 530051, member: 35183"] rcdinaz, there are a very small number of materials with tailored expansion coefficients. These are the special steels used to mount glass on space vehicles and "high end" jets that need reliable glass to metal seals (blackbird, B1 etc). It is also used for very precise optical assemblies where the sun may strike one side of the assembly and not the other, yet still stay in alignment (in space the temperature difference is quite extreme). Typically, it is Invar and Kovar that are used, together with fused silica (very low expansion glass). I have used these materials in the lab, where we make very precise measurements from ambient to 1000C and the measurement error at 1000C is only about 0.002" from the expansion of the fused silica (at 1000C) and the invar support (at about 90C). With rifles, the problem is not so exotic, since the action is made from either a low alloy steel, or typically 416 stainless steel. Now and again, you find someone using 17-4ph. If it is a custom action, get the scope rail machined into the receiver. If not, pick a rail with the most similar material to the action. With aluminum, both A356 (popular cast material) as well as 6061 T6 have an expansion coefficient close to 25 (metric) so it is what it is.... [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
steel base and aluminum rings issues?
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