I figure since Hakan did a video interview about it, maybe it’s time to bring all the testing to the light.
In a nutshell, I experienced a scope zero shift in 2015 from the rifle falling over in the hotel room at the Hide Cup. When i returned home and started testing to find the origin of the shift issue we had the first round of NF Atacr 5-25’s at the time and just had switched from our Schmidt PMII’s. What started as a test with a couple mounts on the range turned into an international effort across over a dozen companies. Some companies provided mounts for testing, others got involved in the testing, many different brands and types of optics were tested, various platforms, literally barrels were burnt out just doing the testing over the next 2 years. In the end all parties found no design fix to the inherent shift in the pic rail design. Spoiler: It can be reduced or almost totally mitigated by greasing the rail. Early on when I thought the scopes may be the issue, I spent a whole day at the S&B US Service center with Jerry Ricker absolutely beating up scopes, guns and mounts testing on the collimator and determined the optics weren’t the problem (that and Ryan Brandt from Big Dog Steel decided to JB Weld his scope into his rings and still had shift). Interesting note; a drop of a rifle from hip height on the scope yields consistent .2-.4 mil shift while a ‘dead blow’ on the objective yields up to 2.3 mils with some mounts. Once the shift occurs, you can retorque the mount cross bolts or hit the chassis of the rifle with a hammer and the shock will center the mount back to its zero position.
I found out greasing the rail fixes the issue by grabbing a set of brand new Badger rings out of the package covered in grease and was tired of prepping mounts so I slapped em on greasy and figured if they held zero I would remount them after a full cleaning. Well, sure enough they didn’t shift. So I said that’s it, I’m running Marty’s rings going forward. Pulled them, cleaned and remounted them. I decided to confirm the install and retested since I couldn’t believe everything shifts .9-2.3mils and these guys didn’t shift at all. Whelp, they shifted when retested and the only thing I did was degrease them. Further testing of all previous mounts greased yielded varying amounts of shift to no shift at all confirming the observation. During these tests, it became apparent overtouquing mounts made the issue worse. So make sure to torque only to mfg specs.
Also tested were oversized Pic Rails, polished pic rails, varying coatings on pic rails, from steel to aluminum. Even other types of rail designs were looked at, such as euro dovetail on AI and Sako rifles, those shifted as well.
Another interesting note is that we never saw scopes shift in any ring set we tried when mounted properly. That’s saying something since we literally were beating up 4x4 blocks with scopes and rolling rifles off the backs of truck for drop testing.
ETA: this is all about an observed windage shift. The number of recoil lugs or cross bolts made no difference. The grease prevents the mount from ‘sticking’ off center and allows it to find its center. The idea is, the mount will shift side to side when impacted, with a deadened blow there is a lack of residual vibration to keep the mount moving until it recenters and that’s why a by violent drop has 1/3 or less the shift of a deadened blow of the hand or a dead blow hammer tapped against the left or right side of the objective.
In a nutshell, I experienced a scope zero shift in 2015 from the rifle falling over in the hotel room at the Hide Cup. When i returned home and started testing to find the origin of the shift issue we had the first round of NF Atacr 5-25’s at the time and just had switched from our Schmidt PMII’s. What started as a test with a couple mounts on the range turned into an international effort across over a dozen companies. Some companies provided mounts for testing, others got involved in the testing, many different brands and types of optics were tested, various platforms, literally barrels were burnt out just doing the testing over the next 2 years. In the end all parties found no design fix to the inherent shift in the pic rail design. Spoiler: It can be reduced or almost totally mitigated by greasing the rail. Early on when I thought the scopes may be the issue, I spent a whole day at the S&B US Service center with Jerry Ricker absolutely beating up scopes, guns and mounts testing on the collimator and determined the optics weren’t the problem (that and Ryan Brandt from Big Dog Steel decided to JB Weld his scope into his rings and still had shift). Interesting note; a drop of a rifle from hip height on the scope yields consistent .2-.4 mil shift while a ‘dead blow’ on the objective yields up to 2.3 mils with some mounts. Once the shift occurs, you can retorque the mount cross bolts or hit the chassis of the rifle with a hammer and the shock will center the mount back to its zero position.
I found out greasing the rail fixes the issue by grabbing a set of brand new Badger rings out of the package covered in grease and was tired of prepping mounts so I slapped em on greasy and figured if they held zero I would remount them after a full cleaning. Well, sure enough they didn’t shift. So I said that’s it, I’m running Marty’s rings going forward. Pulled them, cleaned and remounted them. I decided to confirm the install and retested since I couldn’t believe everything shifts .9-2.3mils and these guys didn’t shift at all. Whelp, they shifted when retested and the only thing I did was degrease them. Further testing of all previous mounts greased yielded varying amounts of shift to no shift at all confirming the observation. During these tests, it became apparent overtouquing mounts made the issue worse. So make sure to torque only to mfg specs.
Also tested were oversized Pic Rails, polished pic rails, varying coatings on pic rails, from steel to aluminum. Even other types of rail designs were looked at, such as euro dovetail on AI and Sako rifles, those shifted as well.
Another interesting note is that we never saw scopes shift in any ring set we tried when mounted properly. That’s saying something since we literally were beating up 4x4 blocks with scopes and rolling rifles off the backs of truck for drop testing.
ETA: this is all about an observed windage shift. The number of recoil lugs or cross bolts made no difference. The grease prevents the mount from ‘sticking’ off center and allows it to find its center. The idea is, the mount will shift side to side when impacted, with a deadened blow there is a lack of residual vibration to keep the mount moving until it recenters and that’s why a by violent drop has 1/3 or less the shift of a deadened blow of the hand or a dead blow hammer tapped against the left or right side of the objective.
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