If you are using an moa rail the offset your scope is no longer level with the bore and will have some affect on drop chart apps
I am having a hard time believing that Wasgas. Can you elaborate?
The barrel points upwards compared to the scope with two places where the bullet crosses point of aim. So barrel isn't level either.......
I believe this is correct. The end effect of the 20 MOA rail is to raise the end of the barrel by 20 MOA. The scope would then remain horizontal and the turrets would track just the same as if there were no 20 MOA rail.
Wasgas, this is something I did not think about. I do have a 20moa rail on it. . .
You've gotten a lot of good advice on this thread already but I have an idea for you to try.Ok, so i'm trying to run the numbers from this mornings shooting. I have gotten myself a little confused so maybe someone smarter can help me with the math. . .
I am zero at 200yds
BC .696
Velocity 2782
Elevation 5800
Temp 44deg
Scope Height 2.18"
Shot 2" high at 645 yards with 11.75MOA dialed into the scope
Shot 12" low at 871 yards with 19.25 MOA dialed
Thanks for any and all help! Kelpy
Not an issue, we dial in rifle with 20 moa all the time and regularly 45-65 moa rails with no issues!!
MOA bases absolutely can have an impact on this situation. Its just geometry and it is real. If you measure scope height in wrong place it will drew up your ballistic program. To prove this measure your scope height at the back of the scope and front of the scope. You will get a different measurement. However if you measure scope height where the crosshairs are the 20 MOA base will not matter.
Also the wrong scope height can have a pretty significant effect on downrange impact.
When I first started using ballistic programs I learned very quickly just playing around with the scope height proved it to be a very minor factor compared to the rest.My 338 will see a 1.4 inch difference at 800 yards due to being a whole half inch of on my scope height. If you measure near the turret with even a crude tool you'll be more than fine to the ranges the OP is running and it's not his issue.
Zero IS a very critical item and one a guy needs to prove by shooting at 100 then at 300 yards with a reasonably close velocity, I tune my zero before going to long ranges which I usually do at 1000 yards where a minor velocity change will be looked at if needed. Using a quality G7 BC from Litz there is no need to tune the BC till you get near transonic and then only maybe.
WildRose............ I'm starting to think your whole problem could be the scope. I had several Vortex Viper PST's that didn't track consistently up and down. If that's your problem you could waste a lot of time said:I agree with verifying the scope with a box test/tall test. I was recently helping on of my buddies set up his rifle and it turned out that his Vortex was not tracking properly.
My 338 will see a 1.4 inch difference at 800 yards due to being a whole half inch of on my scope height. If you measure near the turret with even a crude tool you'll be more than fine to the ranges the OP is running and it's not his issue.