Posted: 11/6/2015 3:06:09 AM EDT
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I re-zeroed my rifle (Ruger Precision in 6.5 C with a Vortex HD Gen II 4.5-27 mounted using Vortex/Seekins rings) and everything is working well except I needed to go up 8.1 mils to zero. Is that excessive? Did I mess something up? Since I did the mounting and leveling myself and it's all new to me, it occurs that I might have made some big fundamental error.
I want to shoot long range whenever I get the chance and I presume such a big correction costs me yardage so any insight is appreciated. Pic of zeroed scope: 
Pic of a probably flukey three shot group at 200 yards  :
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Not quite sure I understand.
You had this rifle zeroed with the same ring/scope combo and re mounted it, and then were 8.1 mils off from previous zero? Or, you just assembled this all for the first time and had to make an 8.1 mil adjustment to get your zero? Your RPR has a 20MOA drop on the receiver's rail. It would make sense that there would be some pretty extreme adjustments required to get your initial zero, so thats about 20 inches at 100 yards. 1 mil at 100 yards is what....3.6 inches? Multiply that by 8 and you're pretty close to that 20 MOA drop in the rail. If anything, it sounds like your vortex was shipped pretty close to mechanically centered, and it appears your rifle was built pretty straight. |
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Quoted:
Not quite sure I understand. You had this rifle zeroed with the same ring/scope combo and re mounted it, and then were 8.1 mils off from previous zero? Or, you just assembled this all for the first time and had to make an 8.1 mil adjustment to get your zero? Your RPR has a 20MOA drop on the receiver's rail. It would make sense that there would be some pretty extreme adjustments required to get your initial zero, so thats about 20 inches at 100 yards. 1 mil at 100 yards is what....3.6 inches? Multiply that by 8 and you're pretty close to that 20 MOA drop in the rail. If anything, it sounds like your vortex was shipped pretty close to mechanically centered, and it appears your rifle was built pretty straight. I rezeroed (actually pulled everything off the rifle and remounted it all) it because I thought it was too far off and, of course, ended up with the same adjustments. What you say makes sense; I guess I didn't really understand how the rail, scope, and POI interacted. After some googling, I found the following explanation which agrees with yours: "The rail is lower in the front than the back. With the scope at it's internal zero and mounted on a 20 MOA rail the point of impact at 100 yards will be 20 MOA high. In other words the scope is pointing down relative to the barrel. Put the crosshairs on the target and the bullet hits 20" high at 100. " I surprised to lose so many turns of adjustment. If I'm reading things correctly the 19.6 mils of elevation I can dial will get me out to 1500 yards and with the 10mils of holdover in the reticle I could extend to just over 1800 yards. I presume that's why ELR shooters need 40 MOA bases. It's all starting to make sense!
Good to hear I didn't mess anything up and my rifle is put well put together. Thanks for the help, gentlemen! |
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Your 20 MOA rail should cause your scope adjustments to be near the bottom of the travel when zeroed so that you have more range to come up if you need it. THIS! 20 MoA is just under 7 mils. That plus the machining and mounting tolerances and you have 8.a Mils. |
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Yeah, I may have the terminology wrong. I'm assuming that when I turned the elevation knob the direction that said "UP," I'd refer to that as up. I have no idea how the mechanics of a scope works (I'm off to do some googling after this post!),does dialing "Up" actually move things down like adjusting a front sight post?
In any case, it still means that the zeroing adjustment I made reduces the amount of elevation I can dial at extended ranges, right? This stuff is all new to me - thanks for the help! |
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Quoted:
...I needed to go up 8.1 mils to zero. Is that excessive? ... It depends. I would've expected no more than 3.5 mils up. It's possible the elevation turret wasn't centered when you started dialing. Vortex advertises 33 mils of adjustment on that scope. How many "mils up" can you dial after your 8.1 mil zero? Here are some loose numbers: 16.5 mils for a centered turret, plus 5.8 mils for the 20 MOA base, minus 3 mils for tolerances, minus 0.5 mils for 200 yard drop, equals 18.8 mils. If you don't have something close to 18.8 mils or more of up left on your elevation turret then yes, I would consider it excessive. |
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Quoted:
It depends. I would've expected no more than 3.5 mils up. It's possible the elevation turret wasn't centered when you started dialing. Vortex advertises 33 mils of adjustment on that scope. How many "mils up" can you dial after your 8.1 mil zero? Here are some loose numbers: 16.5 mils for a centered turret, plus 5.8 mils for the 20 MOA base, minus 3 mils for tolerances, minus 0.5 mils for 200 yard drop, equals 18.8 mils. If you don't have something close to 18.8 mils or more of up left on your elevation turret then yes, I would consider it excessive. Quoted:
Quoted:
...I needed to go up 8.1 mils to zero. Is that excessive? ... It depends. I would've expected no more than 3.5 mils up. It's possible the elevation turret wasn't centered when you started dialing. Vortex advertises 33 mils of adjustment on that scope. How many "mils up" can you dial after your 8.1 mil zero? Here are some loose numbers: 16.5 mils for a centered turret, plus 5.8 mils for the 20 MOA base, minus 3 mils for tolerances, minus 0.5 mils for 200 yard drop, equals 18.8 mils. If you don't have something close to 18.8 mils or more of up left on your elevation turret then yes, I would consider it excessive. Your numbers are close to what I have - after zeroing, I have 19.6 Mils of adjustment up. |