Tapered moa bases?


Feb 1, 2015
I have a question about tapered moa bases. My question is, if I have a 20 MOA base and I ZERO the turrets, doesn't it just negate the base because I zeroed the turret?
For example if I had zeroed my rifle with a 0-MOA base, then decided to put a 20-MOA base and adjusted for the extra 20-MOA and did not re-zero I would actually get the extra 20-MOA; but if I re-zeroed I might as well not got the base.?.?
A canted base allows you a couple of advantages. !) It adds to the total amount of elevation potential of your set up. 2) When shooting longer ranges....it allows the scope to be operated closer to the mid point of adjustment....meaning you aren't close to the limit of internal adjustment...which might cause binding.

So.....By zeroing with a canted base.....you end up dialing the scope down with the internal elevation when compared to a flat base. In essence you've gained more internal elevation potential without changing scopes. You have not negated the canted base......just picked up extra elevation.

If you zeroed for a flat base and then swapped in a 20 moa base without re-zeroing.......you'd be shooting a bunch higher. So, you would want to re-zero if you wanted to impact the same spot as with a flat base.

This becomes more clear when you have data ( dope ) for your particular round. You can visually see how many moa's or mil's are required to shoot to 500, 700, 1000 yards/meters etc. Most will dial in their dope versus trying to do holdovers.
I still don't understand if I zero how I get that extra elevation. The scope I am looking at is 80 moa for elevation (so 40 up/down). If I adjusted for the base and turned the turrets to -20 moa to accommodate the 20 moa base (60 up 20 down), assuming no zero stop, I can see getting that extra elevation. But now if after turning the turrets to accommodate the base and zeroed the turrets again wouldn't it it just make it 40 up/down and negate adding the base? I'm sorry, I may be over thinking this, I am new to scopes as I grew up on iron sights.
Yeah....You are getting messed up with the term "Zeroing." Like you described....if your scope has 80 moa total internal elevation travel......in a perfect level setting....you'd have 40 moa available to dial up and 40 to dial down. So, in that perfect world.....if you install a 20 moa base......you'd hypothetically have 60 moa available to raise your cross hair and have 20 below your 100 yard zero. The issue that is tripping you up.......you will very rarely...if ever go more than a couple moa below your 100 yard zero. But....if you want to shoot out to 1000, 1200 even 1500 yards....you are going to need extra moa. Depending on what round you're using.....you're scope would not have enough elevation ( Come ups ) to get you to the really long distances. That's the beauty of canted bases.....it gives you a bunch more elevation. You really don't want to have to run your scopes at either extreme......maxed out on the top or minimum elevation.....compressing the springs too much.

When you "Zero".....the internal settings remain at a certain point and the turrets are loosened and set to ( Zero ) on the knob. You still have that extra elevation within the scope......because you dialed below that 40 / 40 theoretical middle. You might be at 20-25 from the bottom leaving you 75-80 moa available to dial up to.

When I was saying zero I meant loosening the turret and putting back to "0" after dialing in the elevation for, I would most likely use 100yd, but I wasn't sure if the 20 moa would remain if I did. Sounds like I was over thinking it. Granted most shots will be under 600 yds because of ranges around me, but the rare opportunity to shoot out to that 1000+ yd range I would want my scope and base to be able to do so. Without a canted base I was looking at maxed or near maxed from the scope and reticle depending on actual distance. But sounds like if I do go with a canted base it will make it easier on the scope. Thanks for the clarification.
When the three allen head screws are loosened......the turret cap has been disengaged from the turret mechanism. So re-positioning the cap to read ( 0 ) does not affect the position of the turret mechanism. It just gives you a reference for your zero setting.....if your scope does not have a zero stop.

Canted bases are used a by a bunch of shooters. As an example...one of my 1,000 yard guns had a Sightron SIII 10-50X by 60mm scope. Great scope for 1,000 yard target shooting bu it has only 50 moa of internal adjustment. With my 20 moa base...I had no problem at 100 yards and had plenty of elevation adjustment available to get me to 1,000. Not sure I could have made it to 1,000 with a flat base.

Good Luck.....Hopefully I haven't made this clear as mud for you,

You have to visualize this in a different way. Say your scope has 60MOA of TOTAL travel. That means 30MOA up and 30MOA down ? Comprende ? To compensate for bullet drop, you are just going to use the "up" direction of travel. So in fact, if mounted on a zero MOA base, all you have available is 30MOA less anything you used to zero since the scope rail and bore are never perfectly aligned. With us so far ?

So if you would like to have more than 30MOA available for elevation correction, you get it by tilting the scope down. Use a 20MOA base, that means you have to dial DOWN 20 MOA to get a zero. So now you have 20 + 30 MOA = approximately 50MOA available to correct for bullet drop.

Hope I didn't lose you in that explanation.
I got it when Wayne explained again, but thank you for explaining it even simpler. But I was thinking along the lines, ORIGINALLY, that if I went down that 20 moa to adjust for the 20 moa base that it would negate the base and go back to being 30 up and 30 down and I would be in the same boat as before adding the canted base.
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