Scope Rail/Scope Unimount with added MOA not adding up.

[Lootenplunder]

I have a CZ 457 precision Chassis with 20" CZ MTR Barrel, Area 419 15 MOA rail, cheap rings and a Vortex Viper PST 5 to 25.
I went local Range that has steel out to 700. I had a 50 yard zero stop, and found that i had 40 MOA of vertical travel before i hit limit on elevation turret. I was able to hit out to 400 yds using the EBR holdover. I had 69 MOA total of elevation. Maxed out holdover would be 72 ( 40 in elevation and i think 32 in holdover).

I wanted to upgrade my rings, so i thought why not get a set of 20 MOA rings. Ended up with Badger Ordnance.

Vortex Viper shows 70 MOA of total elevation, so thought adding 20 MOA scope mount to the 40 MOA I had would allow a 50 yard zero and 60 MOA of elevation. I ended up only getting 10 More MOA. What am i doing wrong?
Should I switch Area 419 rail for 30 MOA?

 

[chevy_man]

There is never a guarantee that you will zero in the center of the scope.

It is what it is. Let the rifle talk to you, as you're capable of listening and it frankly isn't...

 

[DFOOSKING]

Tolerance stacking of individual parts. You buy a 10 MOA rail....it may give you 8.5 or 11.5.

Sometimes parts stack up in way that it falls short. No way to know till you try parts.

Measure parts and ask the manufacturer (cuz they will know faster than we will honestly) if you got a proper rail. Rails have been mislabeled or mispackaged as something else.

Sometimes they will send you a proper rail/fix the issue. So ask.