Re-Zero With 20 MOA Base

Jim Parrington

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May 12, 2022
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I have a Tikka 3x Tac A1 with a 0 MOA base. My scope is a Vortex Razor Gen III 6-36x56. When I bore-sighted & zeroed everything went well. Following my zero I checked to see how much elevation I could still dial up. The result was 58 MOA. To go past 1450 yards without holding for elevation I’ll need to get a different base. I plan to put a 20 MOA base on the rifle and then re-mount the scope & re-zero. This is where I am not sure how to proceed. Should I re-zero using my current 0 MOA base zero or should I start from scratch and re bore sight with the 20 MOA base then zero from there? Thanks in advance. Jim
 

Im2bent

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  • Jun 30, 2020
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    You should be able to go with a 40 moa base easily if you want to get even more adjustment.
     
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    sinister

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    How much elevation will you need to go from your zero to 1450 yards? Ideally you want your crosshairs in the middle of the tube for the majority of your shooting (for optical clarity and left-right windage if you're clicking).

    Near Manufacturing makes 25, 45, and 75 MOA Tikka 3X rails.
     
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    308pirate

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  • Apr 25, 2017
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    I have a Tikka 3x Tac A1 with a 0 MOA base. My scope is a Vortex Razor Gen III 6-36x56. When I bore-sighted & zeroed everything went well. Following my zero I checked to see how much elevation I could still dial up. The result was 58 MOA. To go past 1450 yards without holding for elevation I’ll need to get a different base. I plan to put a 20 MOA base on the rifle and then re-mount the scope & re-zero. This is where I am not sure how to proceed. Should I re-zero using my current 0 MOA base zero or should I start from scratch and re bore sight with the 20 MOA base then zero from there? Thanks in advance. Jim
    You need to start all over. Your 0 moa base zero is meaningless going fwd.

    Ignore all the suggestions to use a base with even more inclination. You don't need them.
     
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    spamassassin

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    Me? I'd install the new base, dial another 20, and send it. You'll be on paper and close, zero as normal from there.
    This however I'd do one other thing as discussed below.
    You need to start all over. Your 0 moa base zero is meaningless going fwd.

    Ignore all the suggestions to use a base with even more inclination. You don't need them.
    You say you want to go past 1450, well how far can your bang stick go before entering the transonic? It's probably best to look at the farthest you're going to take things and set up for that. If 1450 is your supersonic limit, then 20moa appears to be it. However, if you want to push things further and your cartridge/bullet selection's performance envelope is up to it then look at the dope you'll need for shooting the farthest you'll realistically take things in the coldest temperatures you'll bother doing it in and inform your base purchase with that data.

    If the Razor has ~120MOA of vertical and you need 100moa of up to do the farthest and coldest air shot you'll ever bother with and you end up with ~78moa of up with a 20moa base, then you know right there that you need a 40moa base. Off the top of my head I seem to recall that I have to get into pretty thin air to need even 85moa of up in a scope and that's pushing a .338LM with 300's beyond a mile in some serious hot weather and like 3k ft above sea level. If you're deliberately transiting the transonic region then obviously the sky's the limit but if not, calculate what you need before deciding what to purchase. You might find that you want one of those whizbang bases that you can dial elevation into or you might find that what you actually need is a Charlie Tarac. You have to do the math to know for sure.

    Perhaps describe your cartridge's performance spec, bullet make/model, the maximum distance you think you want to reach out to and then we can crunch some numbers ourselves and give some better answers. Otherwise, both quotes above are about as good as the feedback is going to get.
     
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