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Posted: 7/5/2026 10:44:32 AM EDT
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Lasers are very susceptible to thermal drift, as Eotech demonstrates, and not just wavelength, but POA/POI. This is a series oh photos I took using my NX8 and Raid Xe, a late 2025 FP model. Attached File Attached File Attached File Attached File Attached File |
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Originally Posted By JohnDough: Lasers are very susceptible to thermal drift, as Eotech demonstrates, and not just wavelength, but POA/POI. This is a series oh photos I took using my NX8 and Raid Xe, a late 2025 FP model. https://www.ar15.com/media/mediaFiles/453733/1000016010_jpg-3790176.JPG https://www.ar15.com/media/mediaFiles/453733/1000016011_jpg-3790177.JPG https://www.ar15.com/media/mediaFiles/453733/1000016023_jpg-3790178.JPG https://www.ar15.com/media/mediaFiles/453733/1000016025_jpg-3790179.JPG https://www.ar15.com/media/mediaFiles/453733/1000016029_jpg-3790180.JPG |
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Could be the rail itself. Aluminum has a large CTE, handguard rails are rigidly mounted at one end with the other cantilever/floated, and rails are not bilaterally symmetric so they will banana to a degree over a large temperature range. A few mrad/moa is not hard at all to achieve in the world of target shift for cameras and lasers. Could also be the sight itself. I do a lot of optics stuff for work (high power lasers) and I don’t expect a lot of weapon mounted lasers to have much (if any) athermalization designed into them. Maybe a titanium or invar/covar optic carriage at best. |
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Originally Posted By Ohio_Man: Could be the rail itself. Aluminum has a large CTE, handguard rails are rigidly mounted at one end with the other cantilever/floated, and rails are not bilaterally symmetric so they will banana to a degree over a large temperature range. A few mrad/moa is not hard at all to achieve in the world of target shift for cameras and lasers. Could also be the sight itself. I do a lot of optics stuff for work (high power lasers) and I don’t expect a lot of weapon mounted lasers to have much (if any) athermalization designed into them. Maybe a titanium or invar/covar optic carriage at best. When the mfal was the only thing heated, it rules out the optic. When the mfal is dialed to the optic after it walks, and then the system returns to ambient and the mfal is observed "off" inverse to the correction, and bullets sent down range all impacted true to the optic, it was the mfal that walked. As to the rail, Ive used urx6 and 7075 Ti barrel nut Wedgelock. On the wedg test this morning, I heated the mfal for less time to 100% prevent heat transfered to the barrel nut, and used a longer rail as well (13" ish iirc). The mfal moved the same as on urx6. |
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