There is an excellent, very technical, article in Precision Shooting magazine by Norman E. Johnson. This is the second article by the author on scopes & before you dismiss the following as more BS he was awarded first place by Leica Camera for the 1992 article. The author has designed an optical device that allows movement of the reticle to be measured as power, elevation, & windage is adjusted. He contends most variable scopes, even expensive ones, experience some shift. An exception, is tactical scopes in general & specifically Leupold & Nightforce. While not mentioned I am sure the S & B fall into this category. An example was given when the power ring caused reticle shift. After about 100 movements from low to high the shift was greatly reduced. I will not bore you with the technical reasons why this works. I will quote some statements. "While observing reticle movement on target as the windage &/or elevation knobs were being turned a fairly high percentage of scopes tested showed erratic response by the reticle as the knobs were turned". " A weak thrust spring pushing on the erector tube could also contribute to this problem". His solution. "We will always finish the windage adjustment by moving the knob to the left & the elevation windage adjustment downward". "If you want right windage applied move the knob a few clicks beyond where you want & then move the knob left". For power setting shifts he suggests "Always arrive at a power sitting by moving the power selector ring from the lowest power you want--never backwards". He also mentions that Leupold subjects their scopes to the "Frame Grabber" for 5,000 impacts without reticle shift. The old Redfield Co. used their "Destroyer" that punished scopes to the equivalent of 3,600 recoil blasts per hour. Two "Ghetto Grade" scopes were purchased, a Tasco & Barska by the author, & used on a highly accurate rifle. After his scope break in procedure the Barska shot groups of .443 & .542 vs. .462 & .460 for a high quality scope. There is a lot of technical stuff I didn't post so I think the article makes a very good read.
