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I've been working on my 10-22 just trying to make it shoot it's absolute best. I have a "not so expensive" Tru-Glow rimfire scope on it that I got mainly because it was silver & matched my rifle. I decided today to take my Bushnell Bone Collector series 3-9X40 scope off of my deer rifle & put it on the 10-22 to see if there was any noticeable difference in the performance of the rifle with a higher quality scope. The Bushnell scope has a set of Butler Creek see thru flip open scope covers on it. With the rifle securely on the sand bags & not moving, the crosshairs dead center of the 1" bull at 50yds with the scope cover in the "closed position". When I flip the scope cover "open" the point of aim moved 1" to the left. I repeatedly opened & closed the cover while making sure the rifle never moved & it was the same thing each time I opened the cover. I took the covers off & continued to sight it in with the intention of putting them back on & trying it out before I left but I got a phone call & had to leave abruptly before getting a chance to do so. I thought maybe it was an "optical illusion" type thing but if the POA changes 1" from the open to the closed position then there will be a 1" difference in the POI respectively correct? After opening the cover I would then have to move the rifle 1" to the right to center on the bull again right? It might not be all that big of a deal on rimfire plinking cans at 25yds but remember this scope is the one I use on my deer rifle & If it is off 1" at 50yds does that mean it would be off 6" at 300yds? Now that's a big deal. I suppose if the clear lense in the cover is not squared up with the objective lens & that optical change is then included in the magnification process & thereby magnified to a higher degree? Like Forrest Gump said "I'm not a very smart man" but that is how my simple mind sees it. I never would have thought to check something like that but I'm glad I caught it because on my deer rifle that could mean a miss on a nice buck or worse yet a wounded deer running off to suffer & perhaps die at a later date & that would be bad either way. Any thoughts on this? Thanks. Biggjimm.

The light rays may be experiencing refraction as they pass through the clear plastic lenses. This shifting of the image may account for the impact changes you have discovered. The only way to know if it is consistent on your hunting rifle is to take it out to a range that has the distance and see what kind of shift you experience with the covers up and down.

R,
Bullseye